HTML
Living Standard — Last Updated 12 December 2024
Living Standard — Last Updated 12 December 2024
Window,
WindowProxy, and Location objectsWindow objectWindowProxy exotic objectLocation interfaceHistory interfaceNavigation interfaceNavigationHistoryEntry interfaceNavigationActivation interfacenavigate eventNotRestoredReasons interfaceWindow,
WindowProxy, and Location objectsAlthough typically objects cannot be accessed across origins, the web platform would not be true to itself if it did not have some legacy exceptions to that rule that the web depends upon.
This section uses the terminology and typographic conventions from the JavaScript specification. [JAVASCRIPT]
When perform a security check is invoked, with a platformObject, identifier, and type, run these steps:
If platformObject is not a Window or Location object,
then return.
For each e of CrossOriginProperties(platformObject):
If SameValue(e.[[Property]], identifier) is true, then:
If type is "method" and e has neither
[[NeedsGet]] nor [[NeedsSet]], then return.
Otherwise, if type is "getter" and
e.[[NeedsGet]] is true, then return.
Otherwise, if type is "setter" and
e.[[NeedsSet]] is true, then return.
If IsPlatformObjectSameOrigin(platformObject) is false, then
throw a "SecurityError" DOMException.
Window and Location objects both have a
[[CrossOriginPropertyDescriptorMap]] internal slot, whose value is initially an empty
map.
The [[CrossOriginPropertyDescriptorMap]] internal slot contains a map
with entries whose keys are (currentGlobal, objectGlobal,
propertyKey)-tuples and values are property descriptors, as a memoization of what is
visible to scripts when currentGlobal inspects a Window or
Location object from objectGlobal. It is filled lazily by
CrossOriginGetOwnPropertyHelper, which consults it on future lookups.
User agents should allow a value held in the map to be garbage collected along with its corresponding key when nothing holds a reference to any part of the value. That is, as long as garbage collection is not observable.
For example, with const href =
Object.getOwnPropertyDescriptor(crossOriginLocation, "href").set the value and its
corresponding key in the map cannot be garbage collected as that would be observable.
User agents may have an optimization whereby they remove key-value pairs from the map when
document.domain is set. This is not observable as document.domain cannot revisit an earlier value.
For example, setting document.domain
to "example.com" on www.example.com means user agents can remove all
key-value pairs from the map where part of the key is www.example.com, as that can never be part
of the origin again and therefore the corresponding value could never be retrieved
from the map.
If O is a Location object, then return «
{ [[Property]]: "href", [[NeedsGet]]: false, [[NeedsSet]]: true },
{ [[Property]]: "replace" } ».
Return «
{ [[Property]]: "window", [[NeedsGet]]: true, [[NeedsSet]]: false },
{ [[Property]]: "self", [[NeedsGet]]: true, [[NeedsSet]]: false },
{ [[Property]]: "location", [[NeedsGet]]: true, [[NeedsSet]]: true },
{ [[Property]]: "close" },
{ [[Property]]: "closed", [[NeedsGet]]: true, [[NeedsSet]]: false },
{ [[Property]]: "focus" },
{ [[Property]]: "blur" },
{ [[Property]]: "frames", [[NeedsGet]]: true, [[NeedsSet]]: false },
{ [[Property]]: "length", [[NeedsGet]]: true, [[NeedsSet]]: false },
{ [[Property]]: "top", [[NeedsGet]]: true, [[NeedsSet]]: false },
{ [[Property]]: "opener", [[NeedsGet]]: true, [[NeedsSet]]: false },
{ [[Property]]: "parent", [[NeedsGet]]: true, [[NeedsSet]]: false },
{ [[Property]]: "postMessage" } ».
This abstract operation does not return a Completion Record.
Indexed properties do not need to be safelisted in this algorithm, as they are
handled directly by the WindowProxy object.
A JavaScript property name P is a cross-origin accessible window property
name if it is "window", "self", "location", "close", "closed",
"focus", "blur", "frames",
"length", "top", "opener",
"parent", "postMessage", or an array index
property name.
If P is "then", %Symbol.toStringTag%,
%Symbol.hasInstance%, or %Symbol.isConcatSpreadable%, then return
PropertyDescriptor{
[[Value]]: undefined,
[[Writable]]: false,
[[Enumerable]]: false,
[[Configurable]]: true }.
Throw a "SecurityError" DOMException.
Return true if the current settings object's origin is same origin-domain with O's relevant settings object's origin, and false otherwise.
This abstract operation does not return a Completion Record.
Here the current settings object roughly corresponds to the "caller",
because this check occurs before the execution
context for the getter/setter/method in question makes its way onto the JavaScript
execution context stack. For example, in the code w.document, this
step is invoked before the document getter is reached as part
of the [[Get]] algorithm for the WindowProxy
w.
If this abstract operation returns undefined and there is no custom behavior, the
caller needs to throw a "SecurityError" DOMException. In
practice this is handled by the caller calling CrossOriginPropertyFallback.
Let crossOriginKey be a tuple consisting of the current settings object, O's relevant settings object, and P.
For each e of CrossOriginProperties(O):
If SameValue(e.[[Property]], P) is true, then:
If the value of the [[CrossOriginPropertyDescriptorMap]] internal slot of O contains an entry whose key is crossOriginKey, then return that entry's value.
Let originalDesc be OrdinaryGetOwnProperty(O, P).
Let crossOriginDesc be undefined.
If e.[[NeedsGet]] and e.[[NeedsSet]] are absent, then:
Let value be originalDesc.[[Value]].
If IsCallable(value) is true, then set value to an anonymous built-in function, created in the current realm, that performs the same steps as the IDL operation P on object O.
Set crossOriginDesc to PropertyDescriptor{ [[Value]]: value, [[Enumerable]]: false, [[Writable]]: false, [[Configurable]]: true }.
Otherwise:
Let crossOriginGet be undefined.
If e.[[NeedsGet]] is true, then set crossOriginGet to an anonymous built-in function, created in the current realm, that performs the same steps as the getter of the IDL attribute P on object O.
Let crossOriginSet be undefined.
If e.[[NeedsSet]] is true, then set crossOriginSet to an anonymous built-in function, created in the current realm, that performs the same steps as the setter of the IDL attribute P on object O.
Set crossOriginDesc to PropertyDescriptor{ [[Get]]: crossOriginGet, [[Set]]: crossOriginSet, [[Enumerable]]: false, [[Configurable]]: true }.
Create an entry in the value of the [[CrossOriginPropertyDescriptorMap]] internal slot of O with key crossOriginKey and value crossOriginDesc.
Return crossOriginDesc.
Return undefined.
This abstract operation does not return a Completion Record.
The reason that the property descriptors produced here are configurable is to preserve the invariants of the essential internal methods required by the JavaScript specification. In particular, since the value of the property can change as a consequence of navigation, it is required that the property be configurable. (However, see tc39/ecma262 issue #672 and references to it elsewhere in this specification for cases where we are not able to preserve these invariants, for compatibility with existing web content.) [JAVASCRIPT]
The reason the property descriptors are non-enumerable, despite this mismatching the same-origin behavior, is for compatibility with existing web content. See issue #3183 for details.
Let desc be ? O.[[GetOwnProperty]](P).
Assert: desc is not undefined.
If IsDataDescriptor(desc) is true, then return desc.[[Value]].
Assert: IsAccessorDescriptor(desc) is true.
Let getter be desc.[[Get]].
If getter is undefined, then throw a "SecurityError"
DOMException.
Return ? Call(getter, Receiver).
Let desc be ? O.[[GetOwnProperty]](P).
Assert: desc is not undefined.
If desc.[[Set]] is present and its value is not undefined, then:
Perform ? Call(setter, Receiver, « V »).
Return true.
Throw a "SecurityError" DOMException.
Let keys be a new empty List.
For each e of CrossOriginProperties(O), append e.[[Property]] to keys.
Return the concatenation of keys and « "then",
%Symbol.toStringTag%, %Symbol.hasInstance%, %Symbol.isConcatSpreadable%
».
This abstract operation does not return a Completion Record.
Window objectSupport in all current engines.
[Global =Window ,
Exposed =Window ,
LegacyUnenumerableNamedProperties ]
interface Window : EventTarget {
// the current browsing context
[LegacyUnforgeable ] readonly attribute WindowProxy window ;
[Replaceable ] readonly attribute WindowProxy self ;
[LegacyUnforgeable ] readonly attribute Document document ;
attribute DOMString name ;
[PutForwards =href , LegacyUnforgeable ] readonly attribute Location location ;
readonly attribute History history ;
readonly attribute Navigation navigation ;
readonly attribute CustomElementRegistry customElements ;
[Replaceable ] readonly attribute BarProp locationbar ;
[Replaceable ] readonly attribute BarProp menubar ;
[Replaceable ] readonly attribute BarProp personalbar ;
[Replaceable ] readonly attribute BarProp scrollbars ;
[Replaceable ] readonly attribute BarProp statusbar ;
[Replaceable ] readonly attribute BarProp toolbar ;
attribute DOMString status ;
undefined close ();
readonly attribute boolean closed ;
undefined stop ();
undefined focus ();
undefined blur ();
// other browsing contexts
[Replaceable ] readonly attribute WindowProxy frames ;
[Replaceable ] readonly attribute unsigned long length ;
[LegacyUnforgeable ] readonly attribute WindowProxy ? top ;
attribute any opener ;
[Replaceable ] readonly attribute WindowProxy ? parent ;
readonly attribute Element ? frameElement ;
WindowProxy ? open (optional USVString url = "", optional DOMString target = "_blank", optional [LegacyNullToEmptyString ] DOMString features = "");
// Since this is the global object, the IDL named getter adds a NamedPropertiesObject exotic
// object on the prototype chain. Indeed, this does not make the global object an exotic object.
// Indexed access is taken care of by the WindowProxy exotic object.
getter object (DOMString name );
// the user agent
readonly attribute Navigator navigator ;
[Replaceable ] readonly attribute Navigator clientInformation ; // legacy alias of .navigator
readonly attribute boolean originAgentCluster ;
// user prompts
undefined alert ();
undefined alert (DOMString message );
boolean confirm (optional DOMString message = "");
DOMString ? prompt (optional DOMString message = "", optional DOMString default = "");
undefined print ();
undefined postMessage (any message , USVString targetOrigin , optional sequence <object > transfer = []);
undefined postMessage (any message , optional WindowPostMessageOptions options = {});
// also has obsolete members
};
Window includes GlobalEventHandlers ;
Window includes WindowEventHandlers ;
dictionary WindowPostMessageOptions : StructuredSerializeOptions {
USVString targetOrigin = "/";
};window.windowSupport in all current engines.
window.framesSupport in all current engines.
window.selfSupport in all current engines.
These attributes all return window.
window.documentSupport in all current engines.
Returns the Document associated with window.
document.defaultViewSupport in all current engines.
Returns the Window associated with document, if there is one, or null otherwise.
The Window object has an associated
Document, which is a Document object. It is set when the
Window object is created, and only ever changed during navigation from the initial
about:blank Document.
A Window's browsing context is
its associated Document's browsing context. It is either null or a
browsing context.
A Window's navigable is
the navigable whose active document is the
Window's associated
Document's, or null if there is no such navigable.
The window, frames, and self getter steps are to return this's relevant realm.[[GlobalEnv]].[[GlobalThisValue]].
The document getter steps
are to return this's associated
Document.
The Document object associated with a Window object can
change in exactly one case: when the navigate algorithm creates a new Document object for the
first page loaded in a browsing context. In that specific case, the
Window object of the initial
about:blank page is reused and gets a new Document object.
The defaultView getter steps are:
If this's browsing context is null, then return null.
Return this's browsing context's
WindowProxy object.
Support in all current engines.
For historical reasons, Window objects must also have a writable, configurable,
non-enumerable property named HTMLDocument whose value is the
Document interface object.
window = window.open([ url [, target [, features ] ] ])Support in all current engines.
Opens a window to show url (defaults to "about:blank"), and returns
it. target (defaults to "_blank") gives the name of the new
window. If a window already exists with that name, it is reused. The features
argument can contain a set of comma-separated tokens:
noopener"noreferrer"These behave equivalently to the noopener and noreferrer link types on hyperlinks.
popup"Encourages user agents to provide a minimal web browser user interface for the new
window. (Impacts the visible getter on all
BarProp objects as well.)
globalThis. open( "https://email.example/message/CAOOOkFcWW97r8yg=SsWg7GgCmp4suVX9o85y8BvNRqMjuc5PXg" , undefined , "noopener,popup" ); window.name [ = value ]Support in all current engines.
Returns the name of the window.
Can be set, to change the name.
window.close()Support in all current engines.
Closes the window.
window.closedSupport in all current engines.
Returns true if the window has been closed, false otherwise.
window.stop()Support in all current engines.
Cancels the document load.
To get noopener for window open, given a Document
sourceDocument, an ordered map tokenizedFeatures, and a
URL record-or-null url, perform the following steps. They return a
boolean.
If url is not null and url's blob URL entry is not null:
Let blobOrigin be url's blob URL entry's environment's origin.
Let topLevelOrigin be sourceDocument's relevant settings object's top-level origin.
If blobOrigin is not same site with topLevelOrigin, then return true.
Let noopener be false.
If tokenizedFeatures["noopener"] exists, then set noopener to the result of parsing tokenizedFeatures["noopener"] as a boolean feature.
Return noopener.
The window open steps, given a string url, a string target, and a string features, are as follows:
If the event loop's termination nesting level is nonzero, then return null.
Let sourceDocument be the entry global object's associated Document.
Let urlRecord be null.
If url is not the empty string, then:
Set urlRecord to the result of encoding-parsing a URL given url, relative to sourceDocument.
If urlRecord is failure, then throw a "SyntaxError"
DOMException.
If target is the empty string, then set target to "_blank".
Let tokenizedFeatures be the result of tokenizing features.
Let noreferrer be false.
If tokenizedFeatures["noreferrer"] exists, then set noreferrer to the result of parsing tokenizedFeatures["noreferrer"] as a boolean feature.
Let noopener be the result of getting noopener for window open with sourceDocument, tokenizedFeatures, and urlRecord.
Remove tokenizedFeatures["noopener"] and tokenizedFeatures["noreferrer"].
Let referrerPolicy be the empty string.
If noreferrer is true, then set noopener to true and set
referrerPolicy to "no-referrer".
Let targetNavigable and windowType be the result of applying the rules for choosing a navigable given target, sourceDocument's node navigable, and noopener.
If there is a user agent that supports control-clicking a link to open it in
a new tab, and the user control-clicks on an element whose onclick handler uses the window.open() API to open a page in an iframe element,
the user agent could override the selection of the target browsing context to instead target a
new tab.
If targetNavigable is null, then return null.
If windowType is either "new and unrestricted" or "new with no opener", then:
Set targetNavigable's active browsing context's is popup to the result of checking if a popup window is requested, given tokenizedFeatures.
Set up browsing context features for targetNavigable's active browsing context given tokenizedFeatures. [CSSOMVIEW]
If urlRecord is null, then set urlRecord to a URL
record representing about:blank.
If urlRecord matches about:blank, then perform the
URL and history update steps given targetNavigable's active document and urlRecord.
This is necessary in case url is something like about:blank?foo. If url is just plain about:blank, this will do nothing.
Otherwise, navigate targetNavigable to urlRecord using sourceDocument, with referrerPolicy set to referrerPolicy and exceptionsEnabled set to true.
Otherwise:
If urlRecord is not null, then navigate targetNavigable to urlRecord using sourceDocument, with referrerPolicy set to referrerPolicy and exceptionsEnabled set to true.
If noopener is false, then set targetNavigable's active browsing context's opener browsing context to sourceDocument's browsing context.
If noopener is true or windowType is "new with no
opener", then return null.
Return targetNavigable's active
WindowProxy.
The open(url, target,
features) method steps are to run the window open steps with
url, target, and features.
The method provides a mechanism for navigating an existing browsing context or opening and navigating an auxiliary browsing context.
To tokenize the features argument:
Let tokenizedFeatures be a new ordered map.
Let position point at the first code point of features.
While position is not past the end of features:
Let name be the empty string.
Let value be the empty string.
Collect a sequence of code points that are feature separators from features given position. This skips past leading separators before the name.
Collect a sequence of code points that are not feature separators from features given position. Set name to the collected characters, converted to ASCII lowercase.
Set name to the result of normalizing the feature name name.
While position is not past the end of features and the code point at position in features is not U 003D (=):
If the code point at position in features is U 002C (,), or if it is not a feature separator, then break.
Advance position by 1.
This skips to the first U 003D (=) but does not skip past a U 002C (,) or a non-separator.
If the code point at position in features is a feature separator:
While position is not past the end of features and the code point at position in features is a feature separator:
If the code point at position in features is U 002C (,), then break.
Advance position by 1.
This skips to the first non-separator but does not skip past a U 002C (,).
Collect a sequence of code points that are not feature separators code points from features given position. Set value to the collected code points, converted to ASCII lowercase.
If name is not the empty string, then set tokenizedFeatures[name] to value.
Return tokenizedFeatures.
To check if a window feature is set, given tokenizedFeatures, featureName, and defaultValue:
If tokenizedFeatures[featureName] exists, then return the result of parsing tokenizedFeatures[featureName] as a boolean feature.
Return defaultValue.
To check if a popup window is requested, given tokenizedFeatures:
If tokenizedFeatures is empty, then return false.
If tokenizedFeatures["popup"] exists, then return the result of parsing
tokenizedFeatures["popup"] as a boolean
feature.
Let location be the result of checking if
a window feature is set, given tokenizedFeatures, "location", and false.
Let toolbar be the result of checking if
a window feature is set, given tokenizedFeatures, "toolbar", and false.
If location and toolbar are both false, then return true.
Let menubar be the result of checking if
a window feature is set, given tokenizedFeatures, "menubar", and false.
If menubar is false, then return true.
Let resizable be the result of checking if
a window feature is set, given tokenizedFeatures, "resizable", and true.
If resizable is false, then return true.
Let scrollbars be the result of checking
if a window feature is set, given tokenizedFeatures, "scrollbars", and false.
If scrollbars is false, then return true.
Let status be the result of checking if
a window feature is set, given tokenizedFeatures, "status", and false.
If status is false, then return true.
Return false.
A code point is a feature separator if it is ASCII whitespace, U 003D (=), or U 002C (,).
For legacy reasons, there are some aliases of some feature names. To normalize a feature name name, switch on name:
screenx"
left".
screeny"
top".
innerwidth"
width".
innerheight"
height".
To parse a boolean feature given a string value:
If value is the empty string, then return true.
If value is "yes", then return
true.
If value is "true", then return
true.
Let parsed be the result of parsing value as an integer.
If parsed is an error, then set it to 0.
Return false if parsed is 0, and true otherwise.
The name getter steps are:
Return this's navigable's target name.
The name setter steps are:
Set this's navigable's active session history entry's document state's navigable target name to the given value.
The name gets reset when the navigable is navigated to another origin.
The close() method steps
are:
If thisTraversable is not a top-level traversable, then return.
If thisTraversable's is closing is true, then return.
Let browsingContext be thisTraversable's active browsing context.
Let sourceSnapshotParams be the result of snapshotting source snapshot params given thisTraversable's active document.
If all the following are true:
thisTraversable is script-closable;
the incumbent global object's browsing context is familiar with browsingContext; and
the incumbent global object's navigable is allowed by sandboxing to navigate thisTraversable, given sourceSnapshotParams,
then:
Set thisTraversable's is closing to true.
Queue a task on the DOM manipulation task source to definitely close thisTraversable.
A navigable is script-closable if its active browsing context is an auxiliary browsing context that was created by a script (as opposed to by an action of the user), or if it is a top-level traversable whose session history entries's size is 1.
The closed getter
steps are to return true if this's browsing context
is null or its is closing is true; otherwise false.
The stop() method steps
are:
Window objectwindow.lengthSupport in all current engines.
Returns the number of document-tree child navigables.
window[index]Returns the WindowProxy corresponding to the indicated document-tree child navigables.
The length getter steps are
to return this's associated
Document's document-tree child navigables's size.
Indexed access to document-tree child navigables is defined through
the [[GetOwnProperty]] internal method of the
WindowProxy object.
Window objectwindow[name]Returns the indicated element or collection of elements.
As a general rule, relying on this will lead to brittle code. Which IDs end up mapping to
this API can vary over time, as new features are added to the web platform, for example. Instead
of this, use document.getElementById() or document.querySelector().
The document-tree child
navigable target name property set of a Window object window is the
return value of running these steps:
Let children be the document-tree child navigables of
window's associated
Document.
Let firstNamedChildren be an empty ordered set.
For each navigable of children:
Let name be navigable's target name.
If name is the empty string, then continue.
If firstNamedChildren contains a navigable whose target name is name, then continue.
Append navigable to firstNamedChildren.
Let names be an empty ordered set.
For each navigable of firstNamedChildren:
Let name be navigable's target name.
If navigable's active document's origin is same origin with window's relevant settings object's origin, then append name to names.
Return names.
The two seperate iterations mean that in the following example, hosted on https://example.org/, assuming https://elsewhere.example/
sets window.name to "spices", evaluating
window.spices after everything has loaded will yield undefined:
< iframe src = https://elsewhere.example.com/ ></ iframe >
< iframe name = spices ></ iframe > The Window object supports named
properties. The supported property names of a Window object
window at any moment consist of the following, in tree order according to
the element that contributed them, ignoring later duplicates:
window's document-tree child navigable target name property set;
the value of the name content attribute for all embed,
form, img, and object elements that
have a non-empty name content attribute and are in a document
tree with window's associated
Document as their root; and
the value of the id content attribute for all HTML
elements that have a non-empty id content attribute and are
in a document tree with window's associated Document as their
root.
To determine the value of a named property
name in a Window object window, the user agent must return the
value obtained using the following steps:
Let objects be the list of named objects of window with the name name.
There will be at least one such object, since the algorithm would otherwise not have been invoked by Web IDL.
If objects contains a navigable, then:
Let container be the first navigable container in
window's associated
Document's descendants whose
content navigable is in objects.
Return container's content navigable's active WindowProxy.
Otherwise, if objects has only one element, return that element.
Otherwise, return an HTMLCollection rooted at window's associated Document, whose filter matches
only named objects of window with
the name name. (By definition, these will all be elements.)
Named objects of Window object
window with the name name, for the purposes of the above algorithm, consist
of the following:
document-tree child navigables of window's associated Document whose target name is name;
embed, form, img, or
object elements that have a name content attribute whose
value is name and are in a document tree with window's associated Document as their
root; and
HTML elements that have an id content attribute
whose value is name and are in a document tree with window's
associated Document as their
root.
Since the Window interface has the [Global] extended attribute, its named properties follow the rules for
named properties objects rather than legacy platform objects.
window.topSupport in all current engines.
Returns the WindowProxy for the top-level traversable.
window.opener [ = value ]Support in all current engines.
Returns the WindowProxy for the opener browsing context.
Returns null if there isn't one or if it has been set to null.
Can be set to null.
window.parentSupport in all current engines.
Returns the WindowProxy for the parent
navigable.
window.frameElementSupport in all current engines.
Returns the navigable container element.
Returns null if there isn't one, and in cross-origin situations.
The top getter steps are:
Return this's navigable's top-level traversable's active
WindowProxy.
The opener getter steps
are:
Let current be this's browsing context.
If current is null, then return null.
If current's opener browsing context is null, then return null.
Return current's opener browsing context's
WindowProxy object.
The opener setter steps are:
If the given value is null and this's browsing context is non-null, then set this's browsing context's opener browsing context to null.
If the given value is non-null, then perform ?
DefinePropertyOrThrow(this, "opener", {
[[Value]]: the given value, [[Writable]]: true, [[Enumerable]]: true, [[Configurable]]: true
}).
Setting window.opener to null clears the opener
browsing context reference. In practice, this prevents future scripts from accessing their
opener browsing context's Window object.
By default, scripts can access their opener browsing context's
Window object through the window.opener getter.
E.g., a script can set window.opener.location, causing the opener
browsing context to navigate.
The parent getter steps
are:
If navigable is null, then return null.
If navigable's parent is not null, then set navigable to navigable's parent.
Return navigable's active
WindowProxy.
The frameElement
getter steps are:
Let current be this's node navigable.
If current is null, then return null.
Let container be current's container.
If container is null, then return null.
If container's node document's origin is not same origin-domain with the current settings object's origin, then return null.
Return container.
An example of when these properties can return null is as follows:
<!DOCTYPE html>
< iframe ></ iframe >
< script >
"use strict" ;
const element = document. querySelector( "iframe" );
const iframeWindow = element. contentWindow;
element. remove();
console. assert( iframeWindow. top === null );
console. assert( iframeWindow. parent === null );
console. assert( iframeWindow. frameElement === null );
</ script > Here the browsing context corresponding to iframeWindow
was nulled out when element was
removed from the document.
For historical reasons, the Window interface had some properties that represented
the visibility of certain web browser interface elements.
For privacy and interoperability reasons, those properties now return values that
represent whether the Window's browsing context's
is popup property is true or false.
Each interface element is represented by a BarProp object:
Support in all current engines.
[Exposed =Window ]
interface BarProp {
readonly attribute boolean visible ;
};window.locationbar.visibleSupport in all current engines.
window.menubar.visibleSupport in all current engines.
window.personalbar.visibleSupport in all current engines.
window.scrollbars.visibleSupport in all current engines.
window.statusbar.visibleSupport in all current engines.
window.toolbar.visibleSupport in all current engines.
Returns true if the Window is not a popup; otherwise, returns false.
Support in all current engines.
The visible getter
steps are:
Let browsingContext be this's relevant global object's browsing context.
If browsingContext is null, then return true.
Return the negation of browsingContext's top-level browsing context's is popup.
The following BarProp objects must exist for each Window object:
BarProp objectBarProp objectBarProp objectBarProp objectBarProp objectBarProp objectThe locationbar
attribute must return the location bar BarProp object.
The menubar
attribute must return the menu bar BarProp object.
The personalbar
attribute must return the personal bar BarProp object.
The scrollbars
attribute must return the scrollbar BarProp object.
The statusbar
attribute must return the status bar BarProp object.
The toolbar
attribute must return the toolbar BarProp object.
For historical reasons, the status attribute on the Window object must,
on getting, return the last string it was set to, and on setting, must set itself to the new
value. When the Window object is created, the attribute must be set to the empty
string. It does not do anything else.
Window objectsTo set up a window environment settings object, given a URL creationURL, a JavaScript execution context execution context, null or an environment reservedEnvironment, a URL topLevelCreationURL, and an origin topLevelOrigin, run these steps:
Let realm be the value of execution context's Realm component.
Let window be realm's global object.
Let settings object be a new environment settings object whose algorithms are defined as follows:
Return execution context.
Return the module map of
window's associated
Document.
Return the current base URL of window's
associated Document.
Return the origin of window's
associated Document.
Return the policy container of
window's associated
Document.
Return true if both of the following hold, and false otherwise:
realm's agent cluster's cross-origin-isolation mode is "concrete", and
window's associated
Document is allowed to use the "cross-origin-isolated" feature.
Return window's associated
Document's load timing info's navigation start
time.
If reservedEnvironment is non-null, then:
Set settings object's id to reservedEnvironment's id, target browsing context to reservedEnvironment's target browsing context, and active service worker to reservedEnvironment's active service worker.
Set reservedEnvironment's id to the empty string.
The identity of the reserved environment is considered to be fully transferred to the created environment settings object. The reserved environment is not searchable by the environment’s id from this point on.
Otherwise, set settings object's id to a new unique opaque string, settings object's target browsing context to null, and settings object's active service worker to null.
Set settings object's creation URL to creationURL, settings object's top-level creation URL to topLevelCreationURL, and settings object's top-level origin to topLevelOrigin.
Set realm's [[HostDefined]] field to settings object.
WindowProxy exotic objectA WindowProxy is an exotic object that wraps a
Window ordinary object, indirecting most operations through to the wrapped object.
Each browsing context has an associated WindowProxy object. When the
browsing context is navigated, the Window
object wrapped by the browsing context's associated WindowProxy object
is changed.
The WindowProxy exotic object must use the ordinary internal methods except where
it is explicitly specified otherwise below.
There is no WindowProxy interface object.
Every WindowProxy object has a [[Window]] internal slot representing the wrapped Window object.
Although WindowProxy is named as a "proxy", it does not do
polymorphic dispatch on its target's internal methods as a real proxy would, due to a desire to
reuse machinery between WindowProxy and Location objects. As long as the
Window object remains an ordinary object this is unobservable and can be implemented
either way.
Let W be the value of the [[Window]] internal slot of this.
If IsPlatformObjectSameOrigin(W) is true, then return ! OrdinaryGetPrototypeOf(W).
Return null.
Return ! SetImmutablePrototype(this, V).
Return true.
Return false.
Let W be the value of the [[Window]] internal slot of this.
If P is an array index property name, then:
Let index be ! ToUint32(P).
Let children be the document-tree child navigables of
W's associated
Document.
Let value be undefined.
If index is less than children's size, then:
Sort children in ascending order, with
navigableA being less than navigableB if navigableA's container was inserted into W's associated Document earlier than
navigableB's container was.
Set value to children[index]'s active WindowProxy.
If value is undefined, then:
If IsPlatformObjectSameOrigin(W) is true, then return undefined.
Throw a "SecurityError" DOMException.
Return PropertyDescriptor{ [[Value]]: value, [[Writable]]: false, [[Enumerable]]: true, [[Configurable]]: true }.
If IsPlatformObjectSameOrigin(W) is true, then return ! OrdinaryGetOwnProperty(W, P).
This is a willful violation of the JavaScript specification's invariants of the essential internal methods to maintain compatibility with existing web content. See tc39/ecma262 issue #672 for more information. [JAVASCRIPT]
Let property be CrossOriginGetOwnPropertyHelper(W, P).
If property is not undefined, then return property.
If property is undefined and P is in W's document-tree child navigable target name property set, then:
Let value be the active
WindowProxy of the named
object of W with the name P.
Return PropertyDescriptor{ [[Value]]: value, [[Enumerable]]: false, [[Writable]]: false, [[Configurable]]: true }.
The reason the property descriptors are non-enumerable, despite this mismatching the same-origin behavior, is for compatibility with existing web content. See issue #3183 for details.
Return ? CrossOriginPropertyFallback(P).
Let W be the value of the [[Window]] internal slot of this.
If IsPlatformObjectSameOrigin(W) is true, then:
If P is an array index property name, return false.
Return ? OrdinaryDefineOwnProperty(W, P, Desc).
This is a willful violation of the JavaScript specification's invariants of the essential internal methods to maintain compatibility with existing web content. See tc39/ecma262 issue #672 for more information. [JAVASCRIPT]
Throw a "SecurityError" DOMException.
Let W be the value of the [[Window]] internal slot of this.
Check if an access between two browsing contexts should be reported, given the current global object's browsing context, W's browsing context, P, and the current settings object.
If IsPlatformObjectSameOrigin(W) is true, then return ? OrdinaryGet(this, P, Receiver).
Return ? CrossOriginGet(this, P, Receiver).
this is passed rather than W as OrdinaryGet and CrossOriginGet will invoke the [[GetOwnProperty]] internal method.
Let W be the value of the [[Window]] internal slot of this.
Check if an access between two browsing contexts should be reported, given the current global object's browsing context, W's browsing context, P, and the current settings object.
If IsPlatformObjectSameOrigin(W) is true, then:
If P is an array index property name, then return false.
Return ? OrdinarySet(W, P, V, Receiver).
Return ? CrossOriginSet(this, P, V, Receiver).
this is passed rather than W as CrossOriginSet will invoke the [[GetOwnProperty]] internal method.
Let W be the value of the [[Window]] internal slot of this.
If IsPlatformObjectSameOrigin(W) is true, then:
If P is an array index property name, then:
Let desc be ! this.[[GetOwnProperty]](P).
If desc is undefined, then return true.
Return false.
Return ? OrdinaryDelete(W, P).
Throw a "SecurityError" DOMException.
Let W be the value of the [[Window]] internal slot of this.
Let maxProperties be W's associated Document's document-tree
child navigables's size.
Let keys be the range 0 to maxProperties, exclusive.
If IsPlatformObjectSameOrigin(W) is true, then return the concatenation of keys and OrdinaryOwnPropertyKeys(W).
Return the concatenation of keys and ! CrossOriginOwnPropertyKeys(W).
Location interfaceSupport in all current engines.
Support in all current engines.
Support in all current engines.
Each Window object is associated with a unique instance of a Location
object, allocated when the Window object is created.
The Location exotic object is defined through a mishmash of IDL,
invocation of JavaScript internal methods post-creation, and overridden JavaScript internal
methods. Coupled with its scary security policy, please take extra care while implementing
this excrescence.
To create a Location object, run these steps:
Let location be a new Location platform
object.
Let valueOf be location's relevant realm.[[Intrinsics]].[[%Object.prototype.valueOf%]].
Perform ! location.[[DefineOwnProperty]]("valueOf", {
[[Value]]: valueOf,
[[Writable]]: false,
[[Enumerable]]: false,
[[Configurable]]: false }).
Perform ! location.[[DefineOwnProperty]](%Symbol.toPrimitive%, { [[Value]]: undefined, [[Writable]]: false, [[Enumerable]]: false, [[Configurable]]: false }).
Set the value of the [[DefaultProperties]] internal slot of location to location.[[OwnPropertyKeys]]().
Return location.
The addition of valueOf and %Symbol.toPrimitive% own
data properties, as well as the fact that all of Location's IDL attributes are marked
[LegacyUnforgeable], is required by legacy code that consulted
the Location interface, or stringified it, to determine the document URL, and then used it in a security-sensitive way.
In particular, the valueOf, %Symbol.toPrimitive%, and [LegacyUnforgeable] stringifier mitigations ensure that code such as
foo[location] = bar or location "" cannot be
misdirected.
document.location [ = value ]window.location [ = value ]Returns a Location object with the current page's location.
Can be set, to navigate to another page.
The Document object's location getter steps are to return
this's relevant global object's Location object, if
this is fully active, and null otherwise.
The Window object's location getter steps are to return this's
Location object.
Location objects provide a representation of the URL of their associated Document, as well as
methods for navigating and reloading
the associated navigable.
[Exposed =Window ]
interface Location { // but see also additional creation steps and overridden internal methods
[LegacyUnforgeable ] stringifier attribute USVString href ;
[LegacyUnforgeable ] readonly attribute USVString origin ;
[LegacyUnforgeable ] attribute USVString protocol ;
[LegacyUnforgeable ] attribute USVString host ;
[LegacyUnforgeable ] attribute USVString hostname ;
[LegacyUnforgeable ] attribute USVString port ;
[LegacyUnforgeable ] attribute USVString pathname ;
[LegacyUnforgeable ] attribute USVString search ;
[LegacyUnforgeable ] attribute USVString hash ;
[LegacyUnforgeable ] undefined assign (USVString url );
[LegacyUnforgeable ] undefined replace (USVString url );
[LegacyUnforgeable ] undefined reload ();
[LegacyUnforgeable , SameObject ] readonly attribute DOMStringList ancestorOrigins ;
};location.toString()location.hrefSupport in all current engines.
Support in all current engines.
Returns the Location object's URL.
Can be set, to navigate to the given URL.
location.originSupport in all current engines.
Returns the Location object's URL's origin.
location.protocolSupport in all current engines.
Returns the Location object's URL's scheme.
Can be set, to navigate to the same URL with a changed scheme.
location.hostSupport in all current engines.
Returns the Location object's URL's host and port (if different from the default
port for the scheme).
Can be set, to navigate to the same URL with a changed host and port.
location.hostnameSupport in all current engines.
Returns the Location object's URL's host.
Can be set, to navigate to the same URL with a changed host.
location.portSupport in all current engines.
Returns the Location object's URL's port.
Can be set, to navigate to the same URL with a changed port.
location.pathnameSupport in all current engines.
Returns the Location object's URL's path.
Can be set, to navigate to the same URL with a changed path.
location.searchSupport in all current engines.
Returns the Location object's URL's query (includes leading "?" if non-empty).
Can be set, to navigate to the same URL with a changed query (ignores leading "?").
location.hashSupport in all current engines.
Returns the Location object's URL's fragment (includes leading "#" if non-empty).
Can be set, to navigate to the same URL with a changed fragment (ignores leading "#").
location.assign(url)Support in all current engines.
Navigates to the given URL.
location.replace(url)Support in all current engines.
Removes the current page from the session history and navigates to the given URL.
location.reload()Support in all current engines.
Reloads the current page.
location.ancestorOriginsReturns a DOMStringList object listing the origins of the ancestor navigables' active documents.
A Location object has an associated relevant Document,
which is its relevant global object's browsing context's active document, if this
Location object's relevant global object's browsing context is non-null, and null otherwise.
A Location object has an associated url,
which is this Location object's relevant Document's URL, if this Location object's relevant
Document is non-null, and about:blank otherwise.
A Location object has an associated ancestor origins list. When a
Location object is created, its ancestor origins list must be set to a
DOMStringList object whose associated list is the list of strings that
the following steps would produce:
Let output be a new list of strings.
Let current be the Location object's relevant
Document.
While current's container document is non-null:
Set current to current's container document.
Append the serialization of current's origin to output.
Return output.
To Location-object navigate a Location object
location to a URL url, optionally given a NavigationHistoryBehavior historyHandling
(default "auto"):
Let navigable be location's relevant global object's navigable.
Let sourceDocument be the incumbent
global object's associated
Document.
If location's relevant Document is not yet
completely loaded, and the incumbent global
object does not have transient activation, then set
historyHandling to "replace".
Navigate navigable to url using sourceDocument, with exceptionsEnabled set to true and historyHandling set to historyHandling.
The href getter
steps are:
If this's relevant Document is non-null and its
origin is not same origin-domain with
the entry settings object's origin, then throw a
"SecurityError" DOMException.
Return this's url, serialized.
The href setter steps are:
If this's relevant Document is null, then
return.
Let url be the result of encoding-parsing a URL given the given value, relative to the entry settings object.
If url is failure, then throw a "SyntaxError"
DOMException.
Location-object navigate this to
url.
The href setter intentionally has no
security check.
The origin
getter steps are:
If this's relevant Document is non-null and its
origin is not same origin-domain with
the entry settings object's origin, then throw a
"SecurityError" DOMException.
Return the serialization of this's url's origin.
The protocol
getter steps are:
If this's relevant Document is non-null and its
origin is not same origin-domain with
the entry settings object's origin, then throw a
"SecurityError" DOMException.
The protocol setter steps are:
If this's relevant Document is null, then
return.
If this's relevant Document's origin is not same origin-domain with the
entry settings object's origin, then throw a
"SecurityError" DOMException.
Let possibleFailure be the result of basic URL
parsing the given value, followed by ":", with copyURL
as url and scheme start state as
state override.
Because the URL parser ignores multiple consecutive colons, providing a value
of "https:" (or even "https::::") is the same as
providing a value of "https".
If possibleFailure is failure, then throw a
"SyntaxError" DOMException.
If copyURL's scheme is not an HTTP(S) scheme, then terminate these steps.
Location-object navigate this to
copyURL.
The host getter
steps are:
If this's relevant Document is non-null and its
origin is not same origin-domain with
the entry settings object's origin, then throw a
"SecurityError" DOMException.
If url's host is null, return the empty string.
If url's port is null, return url's host, serialized.
Return url's host, serialized, followed by ":" and url's port, serialized.
The host setter steps are:
If this's relevant Document is null, then
return.
If this's relevant Document's origin is not same origin-domain with the
entry settings object's origin, then throw a
"SecurityError" DOMException.
If copyURL has an opaque path, then return.
Basic URL parse the given value, with copyURL as url and host state as state override.
Location-object navigate this to
copyURL.
The hostname
getter steps are:
If this's relevant Document is non-null and its
origin is not same origin-domain with
the entry settings object's origin, then throw a
"SecurityError" DOMException.
Return this's url's host, serialized.
The hostname setter steps are:
If this's relevant Document is null, then
return.
If this's relevant Document's origin is not same origin-domain with the
entry settings object's origin, then throw a
"SecurityError" DOMException.
If copyURL has an opaque path, then return.
Basic URL parse the given value, with copyURL as url and hostname state as state override.
Location-object navigate this to
copyURL.
The port getter
steps are:
If this's relevant Document is non-null and its
origin is not same origin-domain with
the entry settings object's origin, then throw a
"SecurityError" DOMException.
Return this's url's port, serialized.
The port setter steps are:
If this's relevant Document is null, then
return.
If this's relevant Document's origin is not same origin-domain with the
entry settings object's origin, then throw a
"SecurityError" DOMException.
If copyURL cannot have a username/password/port, then return.
If the given value is the empty string, then set copyURL's port to null.
Otherwise, basic URL parse the given value, with copyURL as url and port state as state override.
Location-object navigate this to
copyURL.
The pathname
getter steps are:
If this's relevant Document is non-null and its
origin is not same origin-domain with
the entry settings object's origin, then throw a
"SecurityError" DOMException.
Return the result of URL path serializing this
Location object's url.
The pathname setter steps are:
If this's relevant Document is null, then
return.
If this's relevant Document's origin is not same origin-domain with the
entry settings object's origin, then throw a
"SecurityError" DOMException.
If copyURL has an opaque path, then return.
Set copyURL's path to the empty list.
Basic URL parse the given value, with copyURL as url and path start state as state override.
Location-object navigate this to
copyURL.
The search
getter steps are:
If this's relevant Document is non-null and its
origin is not same origin-domain with
the entry settings object's origin, then throw a
"SecurityError" DOMException.
If this's url's query is either null or the empty string, return the empty string.
The search setter steps are:
If this's relevant Document is null, then
return.
If this's relevant Document's origin is not same origin-domain with the
entry settings object's origin, then throw a
"SecurityError" DOMException.
If the given value is the empty string, set copyURL's query to null.
Otherwise, run these substeps:
Let input be the given value with a single leading "?" removed, if any.
Set copyURL's query to the empty string.
Basic URL parse input, with null, the
relevant Document's document's character encoding,
copyURL as url, and query
state as state
override.
Location-object navigate this to
copyURL.
The hash getter
steps are:
If this's relevant Document is non-null and its
origin is not same origin-domain with
the entry settings object's origin, then throw a
"SecurityError" DOMException.
If this's url's fragment is either null or the empty string, return the empty string.
The hash setter steps are:
If this's relevant Document is null, then
return.
If this's relevant Document's origin is not same origin-domain with the
entry settings object's origin, then throw a
"SecurityError" DOMException.
Let input be the given value with a single leading "#"
removed, if any.
Set copyURL's fragment to the empty string.
Basic URL parse input, with copyURL as url and fragment state as state override.
If copyURL's fragment is this's url's fragment, then return.
This bailout is necessary for compatibility with deployed content, which redundantly sets location.hash on scroll. It does not apply to other
mechanisms of fragment navigation, such as the location.href setter or location.assign().
Location-object navigate this to
copyURL.
Unlike the equivalent API for the a and area elements,
the hash setter does not special case the empty string, to
remain compatible with deployed scripts.
The assign(url) method steps are:
If this's relevant Document is null, then
return.
If this's relevant Document's origin is not same origin-domain with the
entry settings object's origin, then throw a
"SecurityError" DOMException.
Let urlRecord be the result of encoding-parsing a URL given url, relative to the entry settings object.
If urlRecord is failure, then throw a "SyntaxError"
DOMException.
Location-object navigate this to
urlRecord.
The replace(url) method steps are:
If this's relevant Document is null, then
return.
Let urlRecord be the result of encoding-parsing a URL given url, relative to the entry settings object.
If urlRecord is failure, then throw a "SyntaxError"
DOMException.
Location-object navigate this to
urlRecord given "replace".
The replace() method intentionally has
no security check.
The reload() method
steps are:
Let document be this's relevant
Document.
If document is null, then return.
If document's origin is not
same origin-domain with the entry settings object's origin, then throw a
"SecurityError" DOMException.
Reload document's node navigable.
The ancestorOrigins getter steps are:
If this's relevant Document is null, then return
an empty list.
If this's relevant Document's origin is not same origin-domain with the
entry settings object's origin, then throw a
"SecurityError" DOMException.
Otherwise, return this's ancestor origins list.
The details of how the ancestorOrigins attribute works are still
controversial and might change. See issue
#1918 for more information.
As explained earlier, the Location exotic object
requires additional logic beyond IDL for security purposes. The Location object must
use the ordinary internal methods except where it is explicitly specified otherwise below.
Also, every Location object has a [[DefaultProperties]] internal slot
representing its own properties at time of its creation.
If IsPlatformObjectSameOrigin(this) is true, then return ! OrdinaryGetPrototypeOf(this).
Return null.
Return ! SetImmutablePrototype(this, V).
Return true.
Return false.
If IsPlatformObjectSameOrigin(this) is true, then:
Let desc be OrdinaryGetOwnProperty(this, P).
If the value of the [[DefaultProperties]] internal slot of this contains P, then set desc.[[Configurable]] to true.
Return desc.
Let property be CrossOriginGetOwnPropertyHelper(this, P).
If property is not undefined, then return property.
Return ? CrossOriginPropertyFallback(P).
If IsPlatformObjectSameOrigin(this) is true, then:
If the value of the [[DefaultProperties]] internal slot of this contains P, then return false.
Return ? OrdinaryDefineOwnProperty(this, P, Desc).
Throw a "SecurityError" DOMException.
If IsPlatformObjectSameOrigin(this) is true, then return ? OrdinaryGet(this, P, Receiver).
Return ? CrossOriginGet(this, P, Receiver).
If IsPlatformObjectSameOrigin(this) is true, then return ? OrdinarySet(this, P, V, Receiver).
Return ? CrossOriginSet(this, P, V, Receiver).
If IsPlatformObjectSameOrigin(this) is true, then return ? OrdinaryDelete(this, P).
Throw a "SecurityError" DOMException.
If IsPlatformObjectSameOrigin(this) is true, then return OrdinaryOwnPropertyKeys(this).
Return CrossOriginOwnPropertyKeys(this).
History interfaceSupport in all current engines.
Support in all current engines.
enum ScrollRestoration { " auto " , " manual " };
[Exposed =Window ]
interface History {
readonly attribute unsigned long length ;
attribute ScrollRestoration scrollRestoration ;
readonly attribute any state ;
undefined go (optional long delta = 0);
undefined back ();
undefined forward ();
undefined pushState (any data , DOMString unused , optional USVString ? url = null );
undefined replaceState (any data , DOMString unused , optional USVString ? url = null );
};history.lengthSupport in all current engines.
Returns the number of overall session history entries for the current traversable navigable.
history.scrollRestorationSupport in all current engines.
Returns the scroll restoration mode of the active session history entry.
history.scrollRestoration = valueSet the scroll restoration mode of the active session history entry to value.
history.stateSupport in all current engines.
Returns the classic history API state of the active session history entry, deserialized into a JavaScript value.
history.go()Reloads the current page.
history.go(delta)Support in all current engines.
Goes back or forward the specified number of steps in the overall session history entries list for the current traversable navigable.
A zero delta will reload the current page.
If the delta is out of range, does nothing.
history.back()Support in all current engines.
Goes back one step in the overall session history entries list for the current traversable navigable.
If there is no previous page, does nothing.
history.forward()Support in all current engines.
Goes forward one step in the overall session history entries list for the current traversable navigable.
If there is no next page, does nothing.
history.pushState(data, "")Support in all current engines.
Adds a new entry into session history with its classic history API state set to a serialization of data. The active history entry's URL will be copied over and used for the new entry's URL.
(The second parameter exists for historical reasons, and cannot be omitted; passing the empty string is traditional.)
history.pushState(data, "", url)Adds a new entry into session history with its classic history API state set to a serialization of data, and with its URL set to url.
If the current Document cannot have
its URL rewritten to url, a "SecurityError"
DOMException will be thrown.
(The second parameter exists for historical reasons, and cannot be omitted; passing the empty string is traditional.)
history.replaceState(data, "")Support in all current engines.
Updates the classic history API state of the active session history entry to a structured clone of data.
(The second parameter exists for historical reasons, and cannot be omitted; passing the empty string is traditional.)
history.replaceState(data, "", url)Updates the classic history API state of the active session history entry to a structured clone of data, and its URL to url.
If the current Document cannot have
its URL rewritten to url, a "SecurityError"
DOMException will be thrown.
(The second parameter exists for historical reasons, and cannot be omitted; passing the empty string is traditional.)
A Document has a history object, a
History object.
The history getter steps
are to return this's associated
Document's history object.
Each History object has state,
initially null.
Each History object has a length, a
non-negative integer, initially 0.
Each History object has an index, a
non-negative integer, initially 0.
Although the index is not directly exposed, it can be inferred from changes to the length during synchronous navigations. In fact, that is what it's used for.
The length getter
steps are:
If this's relevant global object's associated Document is not fully
active, then throw a "SecurityError"
DOMException.
The scrollRestoration getter steps are:
If this's relevant global object's associated Document is not fully
active, then throw a "SecurityError"
DOMException.
Return this's node navigable's active session history entry's scroll restoration mode.
The scrollRestoration setter steps
are:
If this's relevant global object's associated Document is not fully
active, then throw a "SecurityError"
DOMException.
Set this's node navigable's active session history entry's scroll restoration mode to the given value.
The state getter
steps are:
If this's relevant global object's associated Document is not fully
active, then throw a "SecurityError"
DOMException.
The go(delta)
method steps are to delta traverse this given delta.
The back() method steps
are to delta traverse this given −1.
The forward() method
steps are to delta traverse this given 1.
To delta traverse a History object history given an integer
delta:
Let document be history's relevant global object's
associated Document.
If document is not fully active, then throw a
"SecurityError" DOMException.
If delta is 0, then reload document's node navigable, and return.
Traverse the history by a delta given document's node navigable's traversable navigable, delta, and with sourceDocument set to document.
The pushState(data,
unused, url) method steps are to run the shared history
push/replace state steps given this, data, url, and
"push".
The replaceState(data, unused,
url) method steps are to run the shared history push/replace state
steps given this, data, url, and "replace".
The shared history push/replace state steps, given a History
history, a value data, a scalar value string-or-null
url, and a history handling behavior historyHandling, are:
Let document be history's associated Document.
If document is not fully active, then throw a
"SecurityError" DOMException.
Optionally, return. (For example, the user agent might disallow calls to these methods that are invoked on a timer, or from event listeners that are not triggered in response to a clear user action, or that are invoked in rapid succession.)
Let serializedData be StructuredSerializeForStorage(data). Rethrow any exceptions.
Let newURL be document's URL.
If url is not null or the empty string, then:
Set newURL to the result of encoding-parsing a URL given url, relative to the relevant settings object of history.
If newURL is failure, then throw a "SecurityError"
DOMException.
If document cannot have its URL
rewritten to newURL, then throw a "SecurityError"
DOMException.
The special case for the empty string here is historical, and leads to
different resulting URLs when comparing code such as location.href = ""
(which performs URL parsing on the empty string) versus history.pushState(null, "", "") (which bypasses it).
Let navigation be history's relevant global object's navigation API.
Let continue be the result of firing a push/replace/reload navigate event at
navigation with navigationType set to
historyHandling, isSameDocument set
to true, destinationURL set to
newURL, and classicHistoryAPIState set to
serializedData.
If continue is false, then return.
Run the URL and history update steps given document and newURL, with serializedData set to serializedData and historyHandling set to historyHandling.
User agents may limit the number of state objects added to the session history per page. If a
page hits the implementation-defined limit, user agents must remove the entry
immediately after the first entry for that Document object in the session history
after having added the new entry. (Thus the state history acts as a FIFO buffer for eviction, but
as a LIFO buffer for navigation.)
A Document document can have its URL rewritten to a
URL targetURL if the following algorithm returns true:
Let documentURL be document's URL.
If targetURL and documentURL differ in their scheme, username, password, host, or port components, then return false.
If targetURL's scheme is an HTTP(S) scheme, then return true.
Differences in path, query, and fragment are allowed for http: and https: URLs.
If targetURL's scheme is "file", then:
If targetURL and documentURL differ in their path component, then return false.
Return true.
Differences in query and fragment are allowed for file:
URLs.
If targetURL and documentURL differ in their path component or query components, then return false.
Only differences in fragment are allowed for other types of URLs.
Return true.
| document's URL | targetURL | can have its URL rewritten |
|---|---|---|
https://example.com/home
| https://example.com/home#about
| ✅ |
https://example.com/home
| https://example.com/home?page=shop
| ✅ |
https://example.com/home
| https://example.com/shop
| ✅ |
https://example.com/home
| https://user:[email protected]/home
| ❌ |
https://example.com/home
| http://example.com/home
| ❌ |
file:///path/to/x
| file:///path/to/x#hash
| ✅ |
file:///path/to/x
| file:///path/to/x?search
| ✅ |
file:///path/to/x
| file:///path/to/y
| ❌ |
about:blank
| about:blank#hash
| ✅ |
about:blank
| about:blank?search
| ❌ |
about:blank
| about:srcdoc
| ❌ |
data:text/html,foo
| data:text/html,foo#hash
| ✅ |
data:text/html,foo
| data:text/html,foo?search
| ❌ |
data:text/html,foo
| data:text/html,bar
| ❌ |
data:text/html,foo
| data:bar
| ❌ |
blob:https://example.com/77becafe-657b-4fdc-8bd3-e83aaa5e8f43
| blob:https://example.com/77becafe-657b-4fdc-8bd3-e83aaa5e8f43#hash
| ✅ |
blob:https://example.com/77becafe-657b-4fdc-8bd3-e83aaa5e8f43
| blob:https://example.com/77becafe-657b-4fdc-8bd3-e83aaa5e8f43?search
| ❌ |
blob:https://example.com/77becafe-657b-4fdc-8bd3-e83aaa5e8f43
| blob:https://example.com/anything
| ❌ |
blob:https://example.com/77becafe-657b-4fdc-8bd3-e83aaa5e8f43
| blob:path
| ❌ |
Note how only the URL of the Document
matters, and not its origin. They can mismatch in
cases like about:blank Documents with inherited origins, in sandboxed
iframes, or when the document.domain
setter has been used.
Consider a game where the user can navigate along a line, such that the user is always at some coordinate, and such that the user can bookmark the page corresponding to a particular coordinate, to return to it later.
A static page implementing the x=5 position in such a game could look like the following:
<!DOCTYPE HTML>
<!-- this is https://example.com/line?x=5 -->
< html lang = "en" >
< title > Line Game - 5</ title >
< p > You are at coordinate 5 on the line.</ p >
< p >
< a href = "?x=6" > Advance to 6</ a > or
< a href = "?x=4" > retreat to 4</ a > ?
</ p > The problem with such a system is that each time the user clicks, the whole page has to be reloaded. Here instead is another way of doing it, using script:
<!DOCTYPE HTML>
<!-- this starts off as https://example.com/line?x=5 -->
< html lang = "en" >
< title > Line Game - 5</ title >
< p > You are at coordinate < span id = "coord" > 5</ span > on the line.</ p >
< p >
< a href = "?x=6" onclick = "go(1); return false;" > Advance to 6</ a > or
< a href = "?x=4" onclick = "go(-1); return false;" > retreat to 4</ a > ?
</ p >
< script >
var currentPage = 5 ; // prefilled by server
function go( d) {
setupPage( currentPage d);
history. pushState( currentPage, "" , '?x=' currentPage);
}
onpopstate = function ( event) {
setupPage( event. state);
}
function setupPage( page) {
currentPage = page;
document. title = 'Line Game - ' currentPage;
document. getElementById( 'coord' ). textContent = currentPage;
document. links[ 0 ]. href = '?x=' ( currentPage 1 );
document. links[ 0 ]. textContent = 'Advance to ' ( currentPage 1 );
document. links[ 1 ]. href = '?x=' ( currentPage- 1 );
document. links[ 1 ]. textContent = 'retreat to ' ( currentPage- 1 );
}
</ script > In systems without script, this still works like the previous example. However, users that do have script support can now navigate much faster, since there is no network access for the same experience. Furthermore, contrary to the experience the user would have with just a naïve script-based approach, bookmarking and navigating the session history still work.
In the example above, the data argument to the pushState() method is the same information as would be sent
to the server, but in a more convenient form, so that the script doesn't have to parse the URL
each time the user navigates.
Most applications want to use the same scroll restoration mode value for all of
their history entries. To achieve this they can set the scrollRestoration attribute as soon as possible
(e.g., in the first script element in the document's head element) to
ensure that any entry added to the history session gets the desired scroll restoration mode.
< head >
< script >
if ( 'scrollRestoration' in history)
history. scrollRestoration = 'manual' ;
</ script >
</ head >
This section is non-normative.
The navigation API, provided by the global navigation
property, provides a modern and web application-focused way of managing navigations and history entries. It is a successor to the classic location and history APIs.
One ability the API provides is inspecting session history entries. For example, the following will display the entries' URLs in an ordered list:
const ol = document. createElement( "ol" );
ol. start = 0 ; // so that the list items' ordinal values match up with the entry indices
for ( const entry of navigation. entries()) {
const li = document. createElement( "li" );
if ( entry. index < navigation. currentEntry. index) {
li. className = "backward" ;
} else if ( entry. index > navigation. currentEntry. index) {
li. className = "forward" ;
} else {
li. className = "current" ;
}
li. textContent = entry. url;
ol. append( li);
} The navigation.entries() array contains NavigationHistoryEntry instances, which have other useful properties in addition to the url and index properties shown here. Note that the array only contains NavigationHistoryEntry objects that represent the current navigable, and thus its contents are not impacted by navigations inside navigable containers such as iframes, or by navigations of the parent navigable in cases where the navigation API is itself being used inside an iframe. Additionally, it only contains NavigationHistoryEntry objects representing same-origin session history entries, meaning that if the user has visited other origins before or after the current one, there will not be corresponding NavigationHistoryEntrys.
The navigation API can also be used to navigate, reload, or traverse through the history:
< button onclick = "navigation.reload()" > Reload</ button >
< input type = "url" id = "navigationURL" >
< button onclick = "navigation.navigate(navigationURL.value)" > Navigate</ button >
< button id = "backButton" onclick = "navigation.back()" > Back</ button >
< button id = "forwardButton" onclick = "navigation.forward()" > Forward</ button >
< select id = "traversalDestinations" ></ select >
< button id = "goButton" onclick = "navigation.traverseTo(traversalDestinations.value)" > Traverse To</ button >
< script >
backButton. disabled = ! navigation. canGoBack;
forwardButton. disabled = ! navigation. canGoForward;
for ( const entry of navigation. entries()) {
traversalDestinations. append( new Option( entry. url, entry. key));
}
</ script > Note that traversals are again limited to same-origin destinations, meaning that, for example, navigation.canGoBack will be false if the previous session history entry is for a page from another origin.
The most powerful part of the navigation API is the navigate event, which fires whenever almost any navigation or traversal occurs in the current navigable:
navigation. onnavigate = event => {
console. log( event. navigationType); // "push", "replace", "reload", or "traverse"
console. log( event. destination. url);
console. log( event. userInitiated);
// ... and other useful properties
}; (The event will not fire for location bar-initiated navigations, or navigations initiated from other windows, when the destination of the navigation is a new document.)
Much of the time, the event's cancelable property will be true, meaning this event can be canceled using preventDefault():
navigation. onnavigate = event => {
if ( event. cancelable && isDisallowedURL( event. destination. url)) {
alert( `Please don't go to ${ event. destination. url} !` );
event. preventDefault();
}
};
The cancelable property will be false for some "traverse" navigations, such as those taking place inside child navigables, those crossing to new origins, or when the user attempts to traverse again shortly after a previous call to preventDefault() prevented them from doing so.
The NavigateEvent's intercept() method allows intercepting a navigation and converting it into a same-document navigation:
navigation. addEventListener( "navigate" , e => {
// Some navigations, e.g. cross-origin navigations, we cannot intercept.
// Let the browser handle those normally.
if ( ! e. canIntercept) {
return ;
}
// Similarly, don't intercept fragment navigations or downloads.
if ( e. hashChange || e. downloadRequest !== null ) {
return ;
}
const url = new URL( event. destination. url);
if ( url. pathname. startsWith( "/articles/" )) {
e. intercept({
async handler() {
// The URL has already changed, so show a placeholder while
// fetching the new content, such as a spinner or loading page.
renderArticlePagePlaceholder();
// Fetch the new content and display when ready.
const articleContent = await getArticleContent( url. pathname, { signal: e. signal });
renderArticlePage( articleContent);
}
});
}
}); Note that the handler function can return a promise to represent the asynchronous progress, and success or failure, of the navigation. While the promise is still pending, browser UI can treat the navigation as ongoing (e.g., by presenting a loading spinner). Other parts of the navigation API are also sensitive to these promises, such as the return value of navigation.navigate():
const { committed, finished } = await navigation. navigate( "/articles/the-navigation-api-is-cool" );
// The committed promise will fulfill once the URL has changed, which happens
// immediately (as long as the NavigateEvent wasn't canceled).
await committed;
// The finished promise will fulfill once the Promise returned by handler() has
// fulfilled, which happens once the article is downloaded and rendered. (Or,
// it will reject, if handler() fails along the way).
await finished; Navigation interface[Exposed =Window ]
interface Navigation : EventTarget {
sequence <NavigationHistoryEntry > entries ();
readonly attribute NavigationHistoryEntry ? currentEntry ;
undefined updateCurrentEntry (NavigationUpdateCurrentEntryOptions options );
readonly attribute NavigationTransition ? transition ;
readonly attribute NavigationActivation ? activation ;
readonly attribute boolean canGoBack ;
readonly attribute boolean canGoForward ;
NavigationResult navigate (USVString url , optional NavigationNavigateOptions options = {});
NavigationResult reload (optional NavigationReloadOptions options = {});
NavigationResult traverseTo (DOMString key , optional NavigationOptions options = {});
NavigationResult back (optional NavigationOptions options = {});
NavigationResult forward (optional NavigationOptions options = {});
attribute EventHandler onnavigate ;
attribute EventHandler onnavigatesuccess ;
attribute EventHandler onnavigateerror ;
attribute EventHandler oncurrententrychange ;
};
dictionary NavigationUpdateCurrentEntryOptions {
required any state ;
};
dictionary NavigationOptions {
any info ;
};
dictionary NavigationNavigateOptions : NavigationOptions {
any state ;
NavigationHistoryBehavior history = "auto";
};
dictionary NavigationReloadOptions : NavigationOptions {
any state ;
};
dictionary NavigationResult {
Promise <NavigationHistoryEntry > committed ;
Promise <NavigationHistoryEntry > finished ;
};
enum NavigationHistoryBehavior {
" auto " ,
" push " ,
" replace "
};Each Window has an associated navigation
API, which is a Navigation object. Upon creation of the Window
object, its navigation API must be set to a
new Navigation object created in the Window object's relevant realm.
The navigation getter
steps are to return this's navigation
API.
The following are the event handlers (and their corresponding event handler event types) that must be supported,
as event handler IDL attributes, by all objects implementing the
Navigation interface:
| Event handler | Event handler event type |
|---|---|
onnavigate
| navigate
|
onnavigatesuccess
| navigatesuccess
|
onnavigateerror
| navigateerror
|
oncurrententrychange
| currententrychange
|
Each Navigation has an associated entry
list, a list of NavigationHistoryEntry objects, initially
empty.
Each Navigation has an associated current entry index, an integer, initially
−1.
The current entry of a Navigation
navigation is the result of running the following steps:
If navigation has entries and events disabled, then return null.
Assert: navigation's current entry index is not −1.
Return navigation's entry list[navigation's current entry index].
A Navigation navigation has entries and events disabled if
the following steps return true:
Let document be navigation's relevant global object's
associated Document.
If document is not fully active, then return true.
If document's is initial about:blank is true, then
return true.
Return false.
To get the navigation API entry
index of a session history entry she within a
Navigation navigation:
Let index be 0.
For each nhe of navigation's entry list:
If nhe's session history entry is equal to she, then return index.
Increment index by 1.
Return −1.
A key type used throughout the navigation API is the NavigationType
enumeration:
enum NavigationType {
" push " ,
" replace " ,
" reload " ,
" traverse "
};This captures the main web developer-visible types of "navigations", which (as noted elsewhere) do not exactly correspond to this standard's singular navigate algorithm. The meaning of each value is the following:
push"push", or to
history.pushState().replace"replace", or
to history.replaceState().reload"traverse"The value space of the NavigationType enumeration is a superset of
the value space of the specification-internal history handling behavior type. Several
parts of this standard make use of this overlap, by passing in a history handling
behavior to an algorithm that expects a NavigationType.
To initialize the navigation API entries for a new document given a
Navigation navigation, a list of session history entries newSHEs, and a session history
entry initialSHE:
Assert: navigation's entry list is empty.
Assert: navigation's current entry index is −1.
If navigation has entries and events disabled, then return.
For each newSHE of newSHEs:
Let newNHE be a new NavigationHistoryEntry created
in the relevant realm of
navigation.
Set newNHE's session history entry to newSHE.
Append newNHE to navigation's entry list.
newSHEs will have originally come from getting session history entries for the navigation API, and thus each newSHE will be contiguous same origin with initialSHE.
Set navigation's current entry index to the result of getting the navigation API entry index of initialSHE within navigation.
To update the navigation API entries for reactivation given a
Navigation navigation, a list of session history entries newSHEs, and a session history
entry reactivatedSHE:
If navigation has entries and events disabled, then return.
Let newNHEs be a new empty list.
Let oldNHEs be a clone of navigation's entry list.
For each newSHE of newSHEs:
Let newNHE be null.
If oldNHEs contains a
NavigationHistoryEntry matchingOldNHE whose session history entry is newSHE, then:
Set newNHE to matchingOldNHE.
Remove matchingOldNHE from oldNHEs.
Otherwise:
Set newNHE to a new NavigationHistoryEntry
created in the relevant realm of
navigation.
Set newNHE's session history entry to newSHE.
Append newNHE to newNHEs.
newSHEs will have originally come from getting session history entries for the navigation API, and thus each newSHE will be contiguous same origin with reactivatedSHE.
By the end of this loop, all NavigationHistoryEntrys that remain in
oldNHEs represent session history entries
which have been disposed while the Document was in bfcache.
Set navigation's entry list to newNHEs.
Set navigation's current entry index to the result of getting the navigation API entry index of reactivatedSHE within navigation.
Queue a global task on the navigation and traversal task source given navigation's relevant global object to run the following steps:
For each disposedNHE of oldNHEs:
Fire an event named dispose at disposedNHE.
We delay these steps by a task to ensure that dispose
events will fire after the pageshow event. This ensures
that pageshow is the first event a page receives upon
reactivation.
(However, the rest of this algorithm runs before the pageshow event fires. This ensures that navigation.entries() and navigation.currentEntry will have correctly-updated
values during any pageshow event handlers.)
To update the navigation API entries for a same-document navigation given a
Navigation navigation, a session history entry
destinationSHE, and a NavigationType navigationType:
If navigation has entries and events disabled, then return.
Let oldCurrentNHE be the current entry of navigation.
Let disposedNHEs be a new empty list.
If navigationType is "traverse",
then:
Set navigation's current entry index to the result of getting the navigation API entry index of destinationSHE within navigation.
Assert: navigation's current entry index is not −1.
This algorithm is only called for same-document traversals. Cross-document traversals will instead call either initialize the navigation API entries for a new document or update the navigation API entries for reactivation.
Otherwise, if navigationType is "push", then:
Set navigation's current entry index to navigation's current entry index 1.
Let i be navigation's current entry index.
While i < navigation's entry list's size:
Append navigation's entry list[i] to disposedNHEs.
Set i to i 1.
Remove all items in disposedNHEs from navigation's entry list.
Otherwise, if navigationType is "replace", then:
Append oldCurrentNHE to disposedNHEs.
If navigationType is "push" or
"replace", then:
Let newNHE be a new NavigationHistoryEntry created
in the relevant realm of
navigation.
Set newNHE's session history entry to destinationSHE.
Set navigation's entry list[navigation's current entry index] to newNHE.
If navigation's ongoing API method tracker is non-null, then notify about the committed-to entry given navigation's ongoing API method tracker and the current entry of navigation.
It is important to do this before firing the dispose or currententrychange events, since event handlers could
start another navigation, or otherwise change the value of navigation's ongoing
API method tracker.
Prepare to run script given navigation's relevant settings object.
See the discussion for other navigation API events to understand why we do this.
Fire an event named currententrychange at navigation using
NavigationCurrentEntryChangeEvent, with its navigationType attribute
initialized to navigationType and its from initialized to
oldCurrentNHE.
For each disposedNHE of disposedNHEs:
Fire an event named dispose at disposedNHE.
Clean up after running script given navigation's relevant settings object.
In implementations, same-document navigations can cause session history entries to be disposed by falling off the back of the session history entry list. This is not yet handled by the above algorithm (or by any other part of this standard). See issue #8620 to track progress on defining the correct behavior in such cases.
NavigationHistoryEntry interface[Exposed =Window ]
interface NavigationHistoryEntry : EventTarget {
readonly attribute USVString ? url ;
readonly attribute DOMString key ;
readonly attribute DOMString id ;
readonly attribute long long index ;
readonly attribute boolean sameDocument ;
any getState ();
attribute EventHandler ondispose ;
};entry.urlThe URL of this navigation history entry.
This can return null if the entry corresponds to a different Document than the
current one (i.e., if sameDocument
is false), and that Document was fetched with a referrer policy of
"no-referrer" or "origin", since that indicates
the Document in question is hiding its URL even from other same-origin pages.
entry.keyA user agent-generated random UUID string representing this navigation history entry's place
in the navigation history list. This value will be reused by other
NavigationHistoryEntry instances that replace this one due to "replace" navigations, and will survive reloads and
session restores.
This is useful for navigating back to this entry in the navigation history list, using navigation.traverseTo(key).
entry.idA user agent-generated random UUID string representing this specific navigation history
entry. This value will not be reused by other NavigationHistoryEntry
instances. This value will survive reloads and session restores.
This is useful for associating data with this navigation history entry using other storage APIs.
entry.indexThe index of this NavigationHistoryEntry within navigation.entries(), or −1 if the entry is not in
the navigation history entry list.
entry.sameDocumentIndicates whether or not this navigation history entry is for the same
Document as the current one, or not. This will be true, for example, when the entry
represents a fragment navigation or single-page app navigation.
entry.getState()Returns the deserialization of the state stored
in this entry, which was added to the entry using navigation.navigate() or navigation.updateCurrentEntry(). This state
survives reloads and session restores.
Note that in general, unless the state value is a primitive, entry.getState() !== entry.getState(), since a fresh deserialization is
returned each time.
This state is unrelated to the classic history API's history.state.
Each NavigationHistoryEntry has an associated session
history entry, which is a session history entry.
The key of a
NavigationHistoryEntry nhe is given by the return value of the following
algorithm:
If nhe's relevant global object's associated Document is not fully
active, then return the empty string.
Return nhe's session history entry's navigation API key.
The ID of a
NavigationHistoryEntry nhe is given by the return value of the following
algorithm:
If nhe's relevant global object's associated Document is not fully
active, then return the empty string.
Return nhe's session history entry's navigation API ID.
The index of a
NavigationHistoryEntry nhe is given by the return value of the following
algorithm:
If nhe's relevant global object's associated Document is not fully
active, then return −1.
Return the result of getting the navigation API entry index of this's session history entry within this's relevant global object's navigation API.
The url getter steps are:
Let document be this's relevant global object's associated Document.
If document is not fully active, then return the empty string.
Let she be this's session history entry.
If she's document does not equal
document, and she's document
state's request referrer
policy is "no-referrer" or "origin", then
return null.
Return she's URL, serialized.
The key getter steps are to return
this's key.
The id getter steps are to return
this's ID.
The index getter steps are to return
this's index.
The sameDocument getter steps are:
Let document be this's relevant global object's associated Document.
If document is not fully active, then return false.
Return true if this's session history entry's document equals document, and false otherwise.
The getState() method steps are:
If this's relevant global object's associated Document is not fully
active, then return undefined.
Return StructuredDeserialize(this's session history entry's navigation API state). Rethrow any exceptions.
This can in theory throw an exception, if attempting to deserialize a large
ArrayBuffer when not enough memory is available.
The following are the event handlers (and their corresponding event handler event types) that must be supported,
as event handler IDL attributes, by all objects implementing the
NavigationHistoryEntry interface:
| Event handler | Event handler event type |
|---|---|
ondispose
| dispose
|
entries = navigation.entries()Returns an array of NavigationHistoryEntry instances represent the current
navigation history entry list, i.e., all session history
entries for this navigable that are same origin and contiguous
to the current session history entry.
navigation.currentEntryReturns the NavigationHistoryEntry corresponding to the current session history entry.
navigation.updateCurrentEntry({ state })Updates the navigation API state of the current session history entry, without performing a
navigation like navigation.reload() would do.
This method is best used to capture updates to the page that have already happened, and need
to be reflected into the navigation API state. For cases where the state update is meant to
drive a page update, instead use navigation.navigate() or navigation.reload(), which will trigger a navigate event.
navigation.canGoBackReturns true if the current current session
history entry (i.e., currentEntry) is
not the first one in the navigation history entry list (i.e., in entries()). This means that there is a previous
session history entry for this navigable, and its document state's origin is same origin with the current
Document's origin.
navigation.canGoForwardReturns true if the current current session
history entry (i.e., currentEntry) is
not the last one in the navigation history entry list (i.e., in entries()). This means that there is a next session
history entry for this navigable, and its document state's origin is same origin with the current
Document's origin.
The entries()
method steps are:
If this has entries and events disabled, then return the empty list.
Return this's entry list.
Recall that because of Web IDL's sequence type conversion rules, this will
create a new JavaScript array object on each call. That is, navigation.entries() !== navigation.entries().
The currentEntry getter steps are to return the
current entry of this.
The updateCurrentEntry(options)
method steps are:
Let current be the current entry of this.
If current is null, then throw an "InvalidStateError"
DOMException.
Let serializedState be
StructuredSerializeForStorage(options["state"]), rethrowing any
exceptions.
Set current's session history entry's navigation API state to serializedState.
Fire an event named currententrychange at this using
NavigationCurrentEntryChangeEvent, with its navigationType attribute
initialized to null and its from
initialized to current.
The canGoBack getter steps are:
If this has entries and events disabled, then return false.
Assert: this's current entry index is not −1.
If this's current entry index is 0, then return false.
Return true.
The canGoForward getter steps are:
If this has entries and events disabled, then return false.
Assert: this's current entry index is not −1.
If this's current entry index is equal to this's entry list's size − 1, then return false.
Return true.
{ committed, finished } = navigation.navigate(url){ committed, finished } = navigation.navigate(url, options)Navigates the current page to the given url. options can contain the following values:
history can be set to
"replace" to replace the current
session history entry, instead of pushing a new one.
info can be set to any value; it
will populate the info property of the
corresponding NavigateEvent.
state can be set to any
serializable value; it will populate the state
retrieved by navigation.currentEntry.getState() once the
navigation completes, for same-document navigations. (It will be ignored for navigations that
end up cross-document.)
By default this will perform a full navigation (i.e., a cross-document navigation, unless the
given URL differs only in a fragment from the current
one). The navigateEvent.intercept() method can
be used to convert it into a same-document navigation.
The returned promises will behave as follows:
For navigations that get aborted, both promises will reject with an
"AbortError" DOMException.
For same-document navigations created by using the navigateEvent.intercept() method, committed will fulfill immediately, and finished will fulfill or reject according to any
promsies returned by handlers passed to intercept().
For other same-document navigations (e.g., non-intercepted fragment navigations), both promises will fulfill immediately.
For cross-document navigations, or navigations that result in 204 or 205 statuses or `Content-Disposition: attachment` header fields from
the server (and thus do not actually navigate), both promises will never settle.
In all cases, when the returned promises fulfill, it will be with the
NavigationHistoryEntry that was navigated to.
{ committed, finished } = navigation.reload(options)Reloads the current page. options can contain info and state, which behave as described above.
The default behavior of performing a from-network-or-cache reload of the current page can be
overriden by the using the navigateEvent.intercept() method. Doing so will mean
this call only updates state or passes along the appropriate info, plus performing whater actions the navigate event handlers see fit to carry out.
The returned promises will behave as follows:
If the reload is intercepted by using the navigateEvent.intercept() method, committed will fulfill immediately, and finished will fulfill or reject according to any
promsies returned by handlers passed to intercept().
Otherwise, both promises will never settle.
{ committed, finished } = navigation.traverseTo(key){ committed, finished } = navigation.traverseTo(key, { info })Traverses to the closest session
history entry that matches the NavigationHistoryEntry with the given
key. info can be set to any value;
it will populate the info property of the
corresponding NavigateEvent.
If a traversal to that session history entry is already in progress, then this
will return the promises for that original traversal, and info will be ignored.
The returned promises will behave as follows:
If there is no NavigationHistoryEntry in navigation.entries() whose key matches key, both promises will
reject with an "InvalidStateError"
DOMException.
For same-document traversals intercepted by the navigateEvent.intercept() method, committed will fulfill as soon as the traversal
is processed and navigation.currentEntry is
updated, and finished will fulfill or
reject according to any promsies returned by the handlers passed to intercept().
For non-intercepted same-document travesals, both promises will fulfill as soon as the
traversal is processed and navigation.currentEntry is updated.
For cross-document traversals, including attempted cross-document traversals that end up
resulting in a 204 or 205 statuses or `Content-Disposition: attachment` header fields from
the server (and thus do not actually traverse), both promises will never settle.
{ committed, finished } = navigation.back(key){ committed, finished } = navigation.back(key, { info })Traverses to the closest previous session history entry which results in this
navigable traversing, i.e., which corresponds to a different
NavigationHistoryEntry and thus will cause navigation.currentEntry to change. info can be set to any value; it will populate the
info property of the corresponding
NavigateEvent.
If a traversal to that session history entry is already in progress, then this
will return the promises for that original traversal, and info will be ignored.
The returned promises behave equivalently to those returned by traverseTo().
{ committed, finished } = navigation.forward(key){ committed, finished } = navigation.forward(key, { info })Traverses to the closest forward session history entry which results in this
navigable traversing, i.e., which corresponds to a different
NavigationHistoryEntry and thus will cause navigation.currentEntry to change. info can be set to any value; it will populate the
info property of the corresponding
NavigateEvent.
If a traversal to that session history entry is already in progress, then this
will return the promises for that original traversal, and info will be ignored.
The returned promises behave equivalently to those returned by traverseTo().
The navigate(url, options) method
steps are:
Let urlRecord be the result of parsing a URL given url, relative to this's relevant settings object.
If urlRecord is failure, then return an early error result for a
"SyntaxError" DOMException.
Let document be this's relevant global object's associated Document.
If options["history"] is "push", and the navigation must be a
replace given urlRecord and document, then return an early error result for a
"NotSupportedError" DOMException.
Let state be options["state"], if it exists; otherwise, undefined.
Let serializedState be StructuredSerializeForStorage(state). If this throws an exception, then return an early error result for that exception.
It is importantly to perform this step early, since serialization can invoke web developer code, which in turn might change various things we check in later steps.
If document is not fully active, then return an early error result for an
"InvalidStateError" DOMException.
If document's unload counter is greater than 0, then return an
early error result for an
"InvalidStateError" DOMException.
Let info be options["info"], if it exists;
otherwise, undefined.
Let apiMethodTracker be the result of maybe setting the upcoming non-traverse API method tracker for this given info and serializedState.
Navigate document's node
navigable to urlRecord using document, with historyHandling set to options["history"] and navigationAPIState set to
serializedState.
Unlike location.assign() and friends,
which are exposed across origin-domain boundaries,
navigation.navigate() can only be accessed by code
with direct synchronous access to the window.navigation
property. Thus, we avoid the complications about attributing the source document of the
navigation, and we don't need to deal with the allowed by sandboxing to navigate
check and its acccompanying exceptionsEnabled flag. We just
treat all navigations as if they come from the Document corresponding to this
Navigation object itself (i.e., document).
If this's upcoming non-traverse API method tracker is apiMethodTracker, then:
If the upcoming non-traverse API method tracker is still
apiMethodTracker, this means that the navigate algorithm bailed out
before ever getting to the inner navigate event
firing algorithm which would promote that upcoming API method tracker to ongoing.
Set this's upcoming non-traverse API method tracker to null.
Return an early error result for
an "AbortError" DOMException.
Return a navigation API method tracker-derived result for apiMethodTracker.
The reload(options) method steps are:
Let document be this's relevant global object's associated Document.
Let serializedState be StructuredSerializeForStorage(undefined).
If options["state"] exists, then set serializedState to
StructuredSerializeForStorage(options["state"]). If this throws an exception, then
return an early error result for that
exception.
It is importantly to perform this step early, since serialization can invoke web developer code, which in turn might change various things we check in later steps.
Otherwise:
Let current be the current entry of this.
If current is not null, then set serializedState to current's session history entry's navigation API state.
If document is not fully active, then return an early error result for an
"InvalidStateError" DOMException.
If document's unload counter is greater than 0, then return an
early error result for an
"InvalidStateError" DOMException.
Let info be options["info"], if it exists;
otherwise, undefined.
Let apiMethodTracker be the result of maybe setting the upcoming non-traverse API method tracker for this given info and serializedState.
Reload document's node navigable with navigationAPIState set to serializedState.
Return a navigation API method tracker-derived result for apiMethodTracker.
The traverseTo(key, options)
method steps are:
If this's current entry
index is −1, then return an early
error result for an "InvalidStateError"
DOMException.
If this's entry list does not
contain a NavigationHistoryEntry whose session history entry's navigation
API key equals key, then return an early error result for an
"InvalidStateError" DOMException.
Return the result of performing a navigation API traversal given this, key, and options.
The back(options) method steps are:
If this's current entry
index is −1 or 0, then return an early error result for an
"InvalidStateError" DOMException.
Let key be this's entry list[this's current entry index − 1]'s session history entry's navigation API key.
Return the result of performing a navigation API traversal given this, key, and options.
The forward(options) method steps are:
If this's current entry
index is −1 or is equal to this's entry list's size −
1, then return an early error result for
an "InvalidStateError" DOMException.
Let key be this's entry list[this's current entry index 1]'s session history entry's navigation API key.
Return the result of performing a navigation API traversal given this, key, and options.
To perform a navigation API traversal
given a Navigation navigation, a string key, and a
NavigationOptions options:
Let document be navigation's relevant global object's
associated Document.
If document is not fully active, then return an early error result for an
"InvalidStateError" DOMException.
If document's unload counter is greater than 0, then return an
early error result for an
"InvalidStateError" DOMException.
Let current be the current entry of navigation.
If key equals current's session history
entry's navigation API key, then return «[
"committed" → a promise resolved
with current, "finished"
→ a promise resolved with current ]».
If navigation's upcoming traverse API method trackers[key] exists, then return a navigation API method tracker-derived result for navigation's upcoming traverse API method trackers[key].
Let info be options["info"], if it exists;
otherwise, undefined.
Let apiMethodTracker be the result of adding an upcoming traverse API method tracker for navigation given key and info.
Let navigable be document's node navigable.
Let traversable be navigable's traversable navigable.
Let sourceSnapshotParams be the result of snapshotting source snapshot params given document.
Append the following session history traversal steps to traversable:
Let navigableSHEs be the result of getting session history entries given navigable.
Let targetSHE be the session history entry in navigableSHEs whose navigation API key is key. If no such entry exists, then:
Queue a global task on the navigation and traversal task
source given navigation's relevant global object to
reject the finished promise for apiMethodTracker with an
"InvalidStateError" DOMException.
Abort these steps.
This path is taken if navigation's entry list was outdated compared to navigableSHEs, which can occur for brief periods while all the relevant threads and processes are being synchronized in reaction to a history change.
If targetSHE is navigable's active session history entry, then abort these steps.
This can occur if a previously queued traversal already took us to this session history entry. In that case the previous traversal will have dealt with apiMethodTracker already.
Let result be the result of applying the traverse history step given by targetSHE's step to traversable, given sourceSnapshotParams,
navigable, and "none".
If result is "canceled-by-beforeunload", then
queue a global task on the navigation and traversal task source given
navigation's relevant global object to reject the finished
promise for apiMethodTracker with a new
"AbortError" DOMException created in
navigation's relevant realm.
If result is "initiator-disallowed", then queue a
global task on the navigation and traversal task source given
navigation's relevant global object to reject the finished
promise for apiMethodTracker with a new
"SecurityError" DOMException created in
navigation's relevant realm.
When result is "canceled-by-beforeunload" or "initiator-disallowed", the navigate
event was never fired, aborting the ongoing
navigation would not be correct; it would result in a navigateerror event without a preceding navigate event.
In the "canceled-by-navigate" case, navigate is fired, but the inner navigate event firing algorithm will take care of
aborting the ongoing navigation.
Return a navigation API method tracker-derived result for apiMethodTracker.
An early error result for an exception
e is a NavigationResult dictionary instance given by «[ "committed" → a promise rejected with
e, "finished" → a promise
rejected with e ]».
A navigation API method tracker-derived result for a navigation API method
tracker is a NavigationResult dictionary instance given by «[ "committed" → apiMethodTracker's committed promise, "finished" → apiMethodTracker's finished promise ]».
During any given navigation (in the broad sense of the
word), the Navigation object needs to keep track of the following:
| State | Duration | Explanation |
|---|---|---|
The NavigateEvent
| For the duration of event firing | So that if the navigation is canceled while the event is firing, we can cancel the event |
| The event's abort controller | Until all promises returned from handlers passed to intercept() have settled
| So that if the navigation is canceled, we can signal abort |
| Whether a new element was focused | Until all promises returned from handlers passed to intercept() have settled
| So that if one was, focus is not reset |
The NavigationHistoryEntry being navigated to
| From when it is determined, until all promises returned from handlers passed to intercept() have settled
| So that we know what to resolve any committed and finished promises with
|
Any finished promise that was returned
| Until all promises returned from handlers passed to intercept() have settled
| So that we can resolve or reject it appropriately |
| State | Duration | Explanation |
|---|---|---|
Any state
| For the duration of event firing | So that we can update the current entry's navigation API state if the event finishes firing without being canceled |
| State | Duration | Explanation |
|---|---|---|
Any info
| Until the task is queued to fire the navigate event
| So that we can use it to fire the navigate after the trip through the session history traversal queue.
|
Any committed promise that was returned
| Until the session history is updated (inside that same task) | So that we can resolve or reject it appropriately |
Whether intercept() was called
| Until the session history is updated (inside that same task) | So that we can suppress the normal scroll restoration logic in favor of the behavior given by the scroll option
|
We also cannot assume there is only a single navigation requested at any given time, due to web developer code such as:
const p1 = navigation. navigate( url1). finished;
const p2 = navigation. navigate( url2). finished; That is, in this scenario, we need to ensure that while navigating to url2, we still have the promise p1 around so that we can
reject it. We can't just get rid of any ongoing navigation promises the moment the second call to
navigate() happens.
We end up accomplishing all this by associating the following with each
Navigation:
Ongoing navigate event, a
NavigateEvent or null, initially null.
Focus changed during ongoing navigation, a boolean, initially false.
Suppress normal scroll restoration during ongoing navigation, a boolean, initially false.
Ongoing API method tracker, a navigation API method tracker or null, initially null.
Upcoming non-traverse API method tracker, a navigation API method tracker or null, initially null.
Upcoming traverse API method trackers, an ordered map from strings to navigation API method trackers, initially empty.
The state here that is not stored in navigation API method trackers is state which needs to be tracked even for navigations that are not initiated via navigation API methods.
A navigation API method tracker is a struct with the following items:
A navigation object, a
Navigation
A key, a string or null
An info, a JavaScript value
A serialized state, a serialized state or null
A committed-to entry,
a NavigationHistoryEntry or null
A committed promise, a promise
A finished promise, a promise
All this state is then managed via the following algorithms.
To maybe set the upcoming non-traverse API method tracker given a
Navigation navigation, a JavaScript value info, and a
serialized state-or-null serializedState:
Let committedPromise and finishedPromise be new promises created in navigation's relevant realm.
Mark as handled finishedPromise.
Let apiMethodTracker be a new navigation API method tracker with:
Assert: navigation's upcoming non-traverse API method tracker is null.
If navigation does not have entries and events disabled, then set navigation's upcoming non-traverse API method tracker to apiMethodTracker.
If navigation has entries and events disabled, then
committedPromise and finishedPromise will never fulfill (since we never
create a NavigationHistoryEntry object for such Documents, and so we
have nothing to resolve them with); there is no NavigationHistoryEntry to apply
serializedState to; and there is no navigate
event to include info with. So, we don't need to track this API method call after
all.
Return apiMethodTracker.
To add an upcoming traverse API method tracker given a Navigation
navigation, a string destinationKey, and a JavaScript value
info:
Let committedPromise and finishedPromise be new promises created in navigation's relevant realm.
Mark as handled finishedPromise.
See the previous discussion about why this is done.
Let apiMethodTracker be a new navigation API method tracker with:
Set navigation's upcoming traverse API method trackers[key] to apiMethodTracker.
Return apiMethodTracker.
To promote an upcoming API method tracker to ongoing given a Navigation
navigation and a string-or-null destinationKey:
Assert: navigation's ongoing API method tracker is null.
If destinationKey is not null, then:
Assert: navigation's upcoming non-traverse API method tracker is null.
If navigation's upcoming traverse API method trackers[destinationKey] exists, then:
Set navigation's ongoing API method tracker to navigation's upcoming traverse API method trackers[destinationKey].
Remove navigation's upcoming traverse API method trackers[destinationKey].
Otherwise:
Set navigation's ongoing API method tracker to navigation's upcoming non-traverse API method tracker.
Set navigation's upcoming non-traverse API method tracker to null.
To clean up a navigation API method tracker apiMethodTracker:
Let navigation be apiMethodTracker's navigation object.
If navigation's ongoing API method tracker is apiMethodTracker, then set navigation's ongoing API method tracker to null.
Otherwise:
Let key be apiMethodTracker's key.
Assert: key is not null.
Assert: navigation's upcoming traverse API method trackers[key] exists.
Remove navigation's upcoming traverse API method trackers[key].
To notify about the committed-to entry given a navigation API method
tracker apiMethodTracker and a NavigationHistoryEntry
nhe:
Set apiMethodTracker's committed-to entry to nhe.
If apiMethodTracker's serialized state is not null, then set nhe's session history entry's navigation API state to apiMethodTracker's serialized state.
If it's null, then we're traversing to nhe via navigation.traverseTo(), which does not allow changing
the state.
At this point, apiMethodTracker's serialized state is no longer needed. Implementations might want to clear it out to avoid keeping it alive for the lifetime of the navigation API method tracker.
Resolve apiMethodTracker's committed promise with nhe.
At this point, apiMethodTracker's committed promise is only needed in cases where it has not yet been returned to author code. Implementations might want to clear it out to avoid keeping it alive for the lifetime of the navigation API method tracker.
To resolve the finished promise for a navigation API method tracker apiMethodTracker:
Resolve apiMethodTracker's committed promise with its committed-to entry.
Usually, notify about the committed-to entry has previously been called on apiMethodTracker, and so this will do nothing. However, in some cases resolve the finished promise is called directly, in which case this step is necessary.
Resolve apiMethodTracker's finished promise with its committed-to entry.
Clean up apiMethodTracker.
To reject the finished promise for a navigation API method tracker apiMethodTracker with a JavaScript value exception:
Reject apiMethodTracker's committed promise with exception.
This will do nothing if apiMethodTracker's committed promise was previously resolved via notify about the committed-to entry.
Reject apiMethodTracker's finished promise with exception.
Clean up apiMethodTracker.
To abort the ongoing navigation given a Navigation
navigation and an optional DOMException error:
Let event be navigation's ongoing navigate event.
Assert: event is not null.
Set navigation's focus changed during ongoing navigation to false.
Set navigation's suppress normal scroll restoration during ongoing navigation to false.
If error was not given, then let error be a new
"AbortError" DOMException created in
navigation's relevant realm.
If event's dispatch flag is set, then set event's canceled flag to true.
Signal abort on event's abort controller given error.
Set navigation's ongoing navigate
event to null.
Let errorInfo be the result of extracting error information from error.
For example, if this algorithm is reached because of a call to window.stop(), these properties would probably end up
initialized based on the line of script that called window.stop(). But if it's because the user clicked the stop
button, these properties would probably end up with default values like the empty string or
0.
Fire an event named navigateerror at navigation using
ErrorEvent, with additional attributes initialized according to
errorInfo.
If navigation's ongoing API method tracker is non-null, then reject the finished promise for apiMethodTracker with error.
If navigation's transition is not null, then:
Reject navigation's transition's finished promise with error.
Set navigation's transition to null.
To inform the navigation API about aborting navigation in a navigable navigable:
If this algorithm is running on navigable's active window's relevant agent's event loop, then continue on to the following steps. Otherwise, queue a global task on the navigation and traversal task source given navigable's active window to run the following steps.
Let navigation be navigable's active window's navigation API.
If navigation's ongoing navigate
event is null, then return.
Abort the ongoing navigation given navigation.
To inform the navigation API about child navigable destruction given a navigable navigable:
Inform the navigation API about aborting navigation in navigable.
Let navigation be navigable's active window's navigation API.
Let traversalAPIMethodTrackers be a clone of navigation's upcoming traverse API method trackers.
For each apiMethodTracker of
traversalAPIMethodTrackers: reject the finished promise for
apiMethodTracker with a new "AbortError"
DOMException created in navigation's relevant realm.
The ongoing navigation concept is most-directly exposed to web developers through the navigation.transition property, which is an instance of
the NavigationTransition interface:
[Exposed =Window ]
interface NavigationTransition {
readonly attribute NavigationType navigationType ;
readonly attribute NavigationHistoryEntry from ;
readonly attribute Promise <undefined > finished ;
};navigation.transitionA NavigationTransition representing any ongoing navigation that hasn't yet
reached the navigatesuccess or navigateerror stage, if one exists; or null, if there is no
such transition ongoing.
Since navigation.currentEntry (and other
properties like location.href) are updated immediately
upon navigation, this navigation.transition
property is useful for determining when such navigations are not yet fully settled, according to
any handlers passed to navigateEvent.intercept().
navigation.transition.navigationTypeOne of "push", "replace", "reload", or "traverse", indicating what type of navigation this
transition is for.
navigation.transition.fromThe NavigationHistoryEntry from which the transition is coming. This can be
useful to compare against navigation.currentEntry.
navigation.transition.finishedA promise which fulfills at the same time as the navigatesuccess fires, or rejects at the same time the
navigateerror event fires.
Each Navigation has a transition, which is a
NavigationTransition or null, initially null.
The transition getter steps are to return
this's transition.
Each NavigationTransition has an associated navigation type, which is a
NavigationType.
Each NavigationTransition has an associated from entry, which is a
NavigationHistoryEntry.
Each NavigationTransition has an associated finished promise, which is a promise.
The navigationType getter steps are to
return this's navigation
type.
The from getter steps are to return
this's from entry.
The finished getter steps are to return
this's finished
promise.
NavigationActivation interface[Exposed =Window ]
interface NavigationActivation {
readonly attribute NavigationHistoryEntry ? from ;
readonly attribute NavigationHistoryEntry entry ;
readonly attribute NavigationType navigationType ;
};navigation.activationA NavigationActivation containing information about the most recent
cross-document navigation, the navigation that "activated" this Document.
While navigation.currentEntry and the
Document's URL can be updated regularly
due to same-document navigations, navigation.activation stays constant, and its properties
are only updated if the Document is reactivated from history.
navigation.activation.entryA NavigationHistoryEntry, equivalent to the value of the navigation.currentEntry property at the moment the
Document was activated.
navigation.activation.fromA NavigationHistoryEntry, representing the Document that was active
right before the current Document. This will have a value null in case the
previous Document was not same origin with this one or if it was the
initial about:blank
Document.
There are some cases in which either the from or entry NavigationHistoryEntry objects
would not be viable targets for the traverseTo()
method, as they might not be retained in history. For example, the Document can be
activated using location.replace() or its initial
entry could be replaced by history.replaceState(). However, those entries' url property and getState() method are still accessible.
navigation.activation.navigationTypeOne of "push", "replace", "reload", or "traverse", indicating what type of navigation
activated this Document.
Each Navigation has an associated activation, which is null or a
NavigationActivation object, initially null.
Each NavigationActivation has:
old entry, null or a
NavigationHistoryEntry.
new entry, null or a
NavigationHistoryEntry.
navigation type, a
NavigationType.
The activation getter steps are to return
this's activation.
The from getter steps are to return
this's old entry.
The entry getter steps are to return
this's new entry.
The navigationType getter steps are to
return this's navigation type.
navigate eventA major feature of the navigation API is the navigate
event. This event is fired on any navigation (in the broad sense of
the word), allowing web developers to monitor such outgoing navigations. In many cases, the
event is cancelable, which allows preventing the
navigation from happening. And in others, the navigation can be intercepted and replaced with a
same-document navigation by using the intercept() method of the NavigateEvent
class.
NavigateEvent interface[Exposed =Window ]
interface NavigateEvent : Event {
constructor (DOMString type , NavigateEventInit eventInitDict );
readonly attribute NavigationType navigationType ;
readonly attribute NavigationDestination destination ;
readonly attribute boolean canIntercept ;
readonly attribute boolean userInitiated ;
readonly attribute boolean hashChange ;
readonly attribute AbortSignal signal ;
readonly attribute FormData formData ;
readonly attribute DOMString ? downloadRequest ;
readonly attribute any info ;
readonly attribute boolean hasUAVisualTransition ;
undefined intercept (optional NavigationInterceptOptions options = {});
undefined scroll ();
};
dictionary NavigateEventInit : EventInit {
NavigationType navigationType = "push";
required NavigationDestination destination ;
boolean canIntercept = false ;
boolean userInitiated = false ;
boolean hashChange = false ;
required AbortSignal signal ;
FormData ? formData = null ;
DOMString ? downloadRequest = null ;
any info ;
boolean hasUAVisualTransition = false ;
};
dictionary NavigationInterceptOptions {
NavigationInterceptHandler handler ;
NavigationFocusReset focusReset ;
NavigationScrollBehavior scroll ;
};
enum NavigationFocusReset {
" after-transition " ,
" manual "
};
enum NavigationScrollBehavior {
" after-transition " ,
" manual "
};
callback NavigationInterceptHandler = Promise <undefined > ();event.navigationTypeOne of "push", "replace", "reload", or "traverse", indicating what type of navigation this
is.
event.destinationA NavigationDestination representing the destination of the
navigation.
event.canInterceptTrue if intercept() can be called to
intercept this navigation and convert it into a same-document navigation, replacing its usual
behavior; false otherwise.
Generally speaking, this will be true whenever the current Document can
have its URL rewritten to the destination URL, except for in the case of cross-document
"traverse" navigations, where it will always
be false.
event.userInitiatedTrue if this navigation was due to a user clicking on an a element,
submitting a form element, or using the browser UI
to navigate; false otherwise.
event.hashChangeTrue for a fragment navigation; false otherwise.
event.signalAn AbortSignal which will become aborted if the navigation gets canceled, e.g.,
by the user pressing their browser's "Stop" button, or by another navigation interrupting this
one.
The expected pattern is for developers to pass this along to any async operations, such as
fetch(), which they perform as part of handling this navigation.
event.formDataThe FormData representing the submitted form entries for this navigation, if
this navigation is a "push" or "replace" navigation representing a POST form submission; null otherwise.
(Notably, this will be null even for "reload"
or "traverse" navigations that are revisiting
a session history entry that was originally created from a form submission.)
event.downloadRequestRepresents whether or not this navigation was requested to be a download, by using an
a or area element's download attribute:
If a download was not requested, then this property is null.
If a download was requested, returns the filename that was supplied as the download attribute's value. (This could be the empty
string.)
Note that a download being requested does not always mean that a download will happen: for
example, a download might be blocked by browser security policies, or end up being treated as a
"push" navigation for unspecified reasons.
Similarly, a navigation might end up being a download even if it was not requested to be one,
due to the destination server responding with a `Content-Disposition: attachment` header.
Finally, note that the navigate event will not fire at
all for downloads initiated using browser UI affordances, e.g., those created by right-clicking
and choosing to save the target of a link.
event.infoAn arbitrary JavaScript value passed via one of the navigation API methods which initiated this navigation, or undefined if the navigation was initiated by the user or by a different API.
event.hasUAVisualTransitionReturns true if the user agent performed a visual transition for this navigation before dispatching this event. If true, the best user experience will be given if the author synchronously updates the DOM to the post-navigation state.
event.intercept({ handler, focusReset, scroll })Intercepts this navigation, preventing its normal handling and instead converting it into a same-document navigation of the same type to the destination URL.
The handler option can be a
function that returns a promise. The handler function will run after the navigate event has finished firing, and the navigation.currentEntry property has been
synchronously updated. This returned promise is used to signal the duration, and success or
failure, of the navigation. After it settles, the browser signals to the user (e.g., via a
loading spinner UI, or assistive technology) that the navigation is finished. Additionally, it
fires navigatesuccess or navigateerror events as appropriate, which other parts of
the web application can respond to.
By default, using this method will cause focus to reset when any handlers' returned promises
settle. Focus will be reset to the first element with the autofocus attribute set, or the body element if
the attribute isn't present. The focusReset option can be set to "manual" to avoid this behavior.
By default, using this method will delay the browser's scroll restoration logic for "traverse" or "reload" navigations, or its
scroll-reset/scroll-to-a-fragment logic for "push"
or "replace" navigations, until any handlers'
returned promises settle. The scroll
option can be set to "manual" to turn
off any browser-driven scroll behavior entirely for this navigation, or scroll() can be called before the promise settles to
trigger this behavior early.
This method will throw a "SecurityError" DOMException
if canIntercept is false, or if isTrusted is false. It will throw an
"InvalidStateError" DOMException if not called
synchronously, during event dispatch.
event.scroll()For "traverse" or "reload" navigations, restores the scroll position
using the browser's usual scroll restoration logic.
For "push" or "replace" navigations, either resets the scroll
position to the top of the document or scrolls to the fragment specified by destination.url if there is one.
If called more than once, or called after automatic post-transition scroll processing has
happened due to the scroll option
being left as "after-transition", or called
before the navigation has committed, this method will throw an
"InvalidStateError" DOMException.
Each NavigateEvent has an interception state, which is either "none", "intercepted", "committed",
"scrolled", or "finished", initially "none".
Each NavigateEvent has a navigation handler list, a
list of NavigationInterceptHandler callbacks, initially empty.
Each NavigateEvent has a focus
reset behavior, a NavigationFocusReset-or-null, initially null.
Each NavigateEvent has a scroll
behavior, a NavigationScrollBehavior-or-null, initially null.
Each NavigateEvent has an abort controller, an
AbortController-or-null, initially null.
Each NavigateEvent has a classic history API state, a
serialized state or null. It is only used in some cases where the event's navigationType is "push" or "replace", and is set appropriately when the event is
fired.
The navigationType, destination, canIntercept, userInitiated,
hashChange, signal, formData, downloadRequest, info, and hasUAVisualTransition attributes
must return the values they are initialized to.
The intercept(options) method steps
are:
Perform shared checks given this.
If this's canIntercept
attribute was initialized to false, then throw a "SecurityError"
DOMException.
If this's dispatch flag is unset, then throw an
"InvalidStateError" DOMException.
Assert: this's interception state is either "none" or "intercepted".
Set this's interception state to "intercepted".
If options["handler"] exists, then append it to this's
navigation handler
list.
If options["focusReset"] exists, then:
If this's focus reset
behavior is not null, and it is not equal to options["focusReset"], then the user agent may
report a warning to the console indicating that the focusReset option for a previous call
to intercept() was overridden by this new
value, and the previous value will be ignored.
Set this's focus reset
behavior to options["focusReset"].
If options["scroll"]
exists, then:
If this's scroll
behavior is not null, and it is not equal to options["scroll"], then the user agent may
report a warning to the console indicating that the scroll option for a previous call to
intercept() was overridden by this new value,
and the previous value will be ignored.
Set this's scroll
behavior to options["scroll"].
The scroll() method steps are:
Perform shared checks given this.
If this's interception state is not "committed", then throw an "InvalidStateError"
DOMException.
Process scroll behavior given this.
To perform shared checks for a
NavigateEvent event:
If event's relevant global object's associated Document is not fully
active, then throw an "InvalidStateError"
DOMException.
If event's isTrusted attribute was
initialized to false, then throw a "SecurityError"
DOMException.
If event's canceled flag is set, then throw an
"InvalidStateError" DOMException.
NavigationDestination interface[Exposed =Window ]
interface NavigationDestination {
readonly attribute USVString url ;
readonly attribute DOMString key ;
readonly attribute DOMString id ;
readonly attribute long long index ;
readonly attribute boolean sameDocument ;
any getState ();
};event.destination.urlThe URL being navigated to.
event.destination.keyThe value of the key property of the
destination NavigationHistoryEntry, if this is a "traverse" navigation, or the empty string otherwise.
event.destination.idThe value of the id property of the
destination NavigationHistoryEntry, if this is a "traverse" navigation, or the empty string otherwise.
event.destination.indexThe value of the index property of
the destination NavigationHistoryEntry, if this is a "traverse" navigation, or −1 otherwise.
event.destination.sameDocumentIndicates whether or not this navigation is to the same Document as the current
one, or not. This will be true, for example, in the case of fragment navigations or history.pushState() navigations.
Note that this property indicates the original nature of the navigation. If a cross-document
navigation is converted into a same-document navigation using navigateEvent.intercept(), that will not change the
value of this property.
event.destination.getState()For "traverse" navigations, returns the
deserialization of the state stored in the
destination session history entry.
For "push" or "replace" navigations, returns the deserialization of the state passed to navigation.navigate(), if the navigation was initiated
by that method, or undefined it if it wasn't.
For "reload" navigations, returns the deserialization of the state passed to navigation.reload(), if the reload was initiated by that
method, or undefined it if it wasn't.
Each NavigationDestination has a URL, which is a URL.
Each NavigationDestination has an entry, which is a
NavigationHistoryEntry or null.
It will be non-null if and only if the NavigationDestination
corresponds to a "traverse" navigation.
Each NavigationDestination has a state, which is a serialized
state.
Each NavigationDestination has an is same document, which is a
boolean.
The url getter steps are to return
this's URL, serialized.
The key getter steps are:
The id getter steps are:
The index getter steps are:
The sameDocument getter steps are to
return this's is same
document.
The getState() method steps are to return
StructuredDeserialize(this's state).
Other parts of the standard fire the navigate event,
through a series of wrapper algorithms given in this section.
To fire a traverse navigate event at a
Navigation navigation given a session history entry destinationSHE and an optional
user navigation involvement userInvolvement (default "none"):
Let event be the result of creating an event given
NavigateEvent, in navigation's relevant realm.
Set event's classic history API state to null.
Let destination be a new NavigationDestination
created in navigation's relevant
realm.
Let destinationNHE be the NavigationHistoryEntry in
navigation's entry list whose session history entry is destinationSHE, or null if no such
NavigationHistoryEntry exists.
If destinationNHE is non-null, then:
Set destination's entry to destinationNHE.
Set destination's state to destinationSHE's navigation API state.
Otherwise,
Set destination's entry to null.
Set destination's state to StructuredSerializeForStorage(null).
Set destination's is
same document to true if destinationSHE's document is equal to navigation's relevant global
object's associated Document;
otherwise false.
Return the result of performing the inner navigate event firing algorithm given
navigation, "traverse",
event, destination, userInvolvement, null, and null.
To fire a push/replace/reload navigate event at
a Navigation navigation given a NavigationType navigationType, a URL destinationURL, a boolean isSameDocument, an optional user
navigation involvement userInvolvement (default "none"), an optional entry list-or-null formDataEntryList (default null), an
optional serialized state navigationAPIState (default
StructuredSerializeForStorage(null)), and an optional serialized
state-or-null classicHistoryAPIState (default
null):
Let event be the result of creating an event given
NavigateEvent, in navigation's relevant realm.
Set event's classic history API state to classicHistoryAPIState.
Let destination be a new NavigationDestination
created in navigation's relevant
realm.
Set destination's URL to destinationURL.
Set destination's entry to null.
Set destination's state to navigationAPIState.
Set destination's is same document to isSameDocument.
Return the result of performing the inner navigate event firing algorithm given
navigation, navigationType, event, destination,
userInvolvement, formDataEntryList, and null.
To fire a download request navigate event at a
Navigation navigation given a URL destinationURL, a user
navigation involvement userInvolvement, and a string
filename:
Let event be the result of creating an event given
NavigateEvent, in navigation's relevant realm.
Set event's classic history API state to null.
Let destination be a new NavigationDestination
created in navigation's relevant
realm.
Set destination's URL to destinationURL.
Set destination's entry to null.
Set destination's state to StructuredSerializeForStorage(null).
Set destination's is same document to false.
Return the result of performing the inner navigate event firing algorithm given
navigation, "push", event,
destination, userInvolvement, null, and filename.
The inner navigate event firing algorithm
consists of the following steps, given a Navigation navigation, a
NavigationType navigationType, a NavigateEvent
event, a NavigationDestination destination, a user
navigation involvement userInvolvement, an entry list-or-null
formDataEntryList, and a string-or-null downloadRequestFilename:
If navigation has entries and events disabled, then:
Assert: navigation's ongoing API method tracker is null.
Assert: navigation's upcoming non-traverse API method tracker is null.
Assert: navigation's upcoming traverse API method trackers is empty.
Return true.
These assertions holds because traverseTo(), back(), and forward() will immediately fail when entries and events
are disabled (since there are no entries to traverse to), and if our starting point is instead
navigate() or reload(), then we avoided setting the
upcoming non-traverse API method tracker in the first place.
Let destinationKey be null.
If destination's entry is non-null, then set destinationKey to destination's entry's key.
Assert: destinationKey is not the empty string.
Promote an upcoming API method tracker to ongoing given navigation and destinationKey.
Let apiMethodTracker be navigation's ongoing API method tracker.
Let navigable be navigation's relevant global object's navigable.
Let document be navigation's relevant global object's
associated Document.
If document can have its URL rewritten to destination's
URL, and either destination's
is same document is true or
navigationType is not "traverse",
then initialize event's canIntercept to true. Otherwise, initialize it to
false.
If either:
navigationType is not "traverse"; or
traverseCanBeCanceled is true,
then initialize event's cancelable to
true. Otherwise, initialize it to false.
Initialize event's navigationType to
navigationType.
Initialize event's destination to destination.
Initialize event's downloadRequest to
downloadRequestFilename.
If apiMethodTracker is not null, then initialize event's info to apiMethodTracker's info. Otherwise, initialize it to
undefined.
At this point apiMethodTracker's info is no longer needed and can be nulled out instead of keeping it alive for the lifetime of the navigation API method tracker.
Initialize event's hasUAVisualTransition to true if a visual
transition, to display a cached rendered state of the document's latest
entry, was done by the user agent. Otherwise, initialize it to false.
Set event's abort
controller to a new AbortController created in
navigation's relevant realm.
Initialize event's signal to
event's abort
controller's signal.
Let currentURL be document's URL.
If all of the following are true:
event's classic history API state is null;
destination's is same document is true;
destination's URL equals currentURL with exclude fragments set to true; and
destination's URL's fragment is not identical to currentURL's fragment,
then initialize event's hashChange to true. Otherwise, initialize it to
false.
The first condition here means that hashChange will be true for fragment navigations, but false for cases like history.pushState(undefined, "", "#fragment").
If userInvolvement is not "none", then
initialize event's userInitiated
to true. Otherwise, initialize it to false.
If formDataEntryList is not null, then initialize event's formData to a new FormData
created in navigation's relevant realm,
associated to formDataEntryList. Otherwise, initialize it to null.
Assert: navigation's ongoing navigate event is null.
Set navigation's ongoing navigate
event to event.
Set navigation's focus changed during ongoing navigation to false.
Set navigation's suppress normal scroll restoration during ongoing navigation to false.
Let dispatchResult be the result of dispatching event at navigation.
If dispatchResult is false:
If navigationType is "traverse", then consume history-action user
activation given navigation's relevant global object.
If event's abort controller's signal is not aborted, then abort the ongoing navigation given navigation.
Return false.
Let endResultIsSameDocument be true if event's interception state is not "none" or event's destination's is same document is true.
Prepare to run script given navigation's relevant settings object.
If event's interception
state is not "none":
Set event's interception state to "committed".
Let fromNHE be the current entry of navigation.
Assert: fromNHE is not null.
Set navigation's transition to a new
NavigationTransition created in navigation's relevant realm, whose navigation type is
navigationType, whose from entry
is fromNHE, and whose finished
promise is a new promise created in navigation's relevant realm.
Mark as handled navigation's transition's finished promise.
See the discussion about other finished promises to understand why this is done.
If navigationType is "traverse", then set navigation's
suppress normal scroll restoration during ongoing navigation to true.
If event's scroll
behavior was set to "after-transition", then scroll
restoration will happen as part of finishing the
relevant NavigateEvent. Otherwise, there will be no scroll restoration. That is,
no navigation which is intercepted by intercept() goes through the normal scroll
restoration process; scroll restoration for such navigations is either done manually, by the
web developer, or is done after the transition.
If navigationType is "push" or
"replace", then run the URL and history
update steps given document and event's destination's URL, with serialiedData set to event's classic history API state and
historyHandling set to navigationType.
If navigationType is "reload",
then we are converting a reload into a "same-document reload", for which the
URL and history update steps are not appropriate. Navigation API-related stuff
still happens, such as updating the active session
history entry's navigation API state if
this was caused by a call to navigation.reload(),
and all the ongoing navigation tracking.
If navigationType is "traverse", then this event firing is happening as
part of the traversal process, and that
process will take care of performing the appropriate session history entry updates.
If endResultIsSameDocument is true:
Let promisesList be an empty list.
For each handler of event's navigation handler list:
If promisesList's size is 0, then set promisesList to « a promise resolved with undefined ».
There is a subtle timing difference between how waiting for all schedules its success and failure steps when given zero promises
versus ≥1 promises. For most uses of waiting for all,
this does not matter. However, with this API, there are so many events and promise handlers
which could fire around the same time that the difference is pretty easily observable: it can
cause the event/promise handler sequence to vary. (Some of the events and promises involved
include: navigatesuccess / navigateerror, currententrychange, dispose, apiMethodTracker's promises, and the navigation.transition.finished promise.)
Wait for all of promisesList, with the following success steps:
If event's relevant global object is not fully active, then abort these steps.
If event's abort controller's signal is aborted, then abort these steps.
Assert: event equals navigation's ongoing
navigate event.
Set navigation's ongoing navigate event to null.
Finish event given true.
Fire an event named navigatesuccess at navigation.
If apiMethodTracker is non-null, then resolve the finished promise for apiMethodTracker.
If navigation's transition is not null, then resolve navigation's transition's finished promise with undefined.
Set navigation's transition to null.
and the following failure steps given reason rejectionReason:
If event's relevant global object is not fully active, then abort these steps.
If event's abort controller's signal is aborted, then abort these steps.
Assert: event equals navigation's ongoing
navigate event.
Set navigation's ongoing navigate event to null.
Finish event given false.
Let errorInfo be the result of extracting error information from rejectionReason.
Fire an event named navigateerror at navigation using
ErrorEvent, with additional attributes initialized according to
errorInfo.
If apiMethodTracker is non-null, then reject the finished promise for apiMethodTracker with rejectionReason.
If navigation's transition is not null, then reject navigation's transition's finished promise with rejectionReason.
Set navigation's transition to null.
Otherwise, if apiMethodTracker is non-null, then clean up apiMethodTracker.
Clean up after running script given navigation's relevant settings object.
Per the previous note, this stops suppressing any potential promise handler microtasks, causing them to run at this point or later.
If event's interception
state is "none", then return true.
Return false.
By calling navigateEvent.intercept(), web
developers can suppress the normal scroll and focus behavior for same-document navigations,
instead invoking cross-document navigation-like behavior at a later time. The algorithms in this
section are called at those appropriate later points.
To finish a NavigateEvent
event, given a boolean didFulfill:
Assert: event's interception state is not "intercepted" or "finished".
If event's interception
state is "none", then return.
Potentially reset the focus given event.
If didFulfill is true, then potentially process scroll behavior given event.
Set event's interception state to "finished".
To potentially reset the focus given a NavigateEvent
event:
Assert: event's interception state is "committed" or "scrolled".
Let navigation be event's relevant global object's navigation API.
Let focusChanged be navigation's focus changed during ongoing navigation.
Set navigation's focus changed during ongoing navigation to false.
If focusChanged is true, then return.
If event's focus reset
behavior is "manual", then
return.
If it was left as null, then we treat that as "after-transition", and continue
onward.
Let document be event's relevant global object's associated Document.
Let focusTarget be the autofocus delegate for document.
If focusTarget is null, then set focusTarget to document's body element.
If focusTarget is null, then set focusTarget to document's document element.
Run the focusing steps for focusTarget, with document's viewport as the fallback target.
Move the sequential focus navigation starting point to focusTarget.
To potentially process scroll behavior given a NavigateEvent
event:
Assert: event's interception state is "committed" or "scrolled".
If event's interception
state is "scrolled", then return.
If event's scroll behavior is
"manual", then return.
If it was left as null, then we treat that as "after-transition", and continue
onward.
Process scroll behavior given event.
To process scroll behavior given a NavigateEvent event:
Assert: event's interception state is "committed".
Set event's interception state to "scrolled".
If event's navigationType was initialized to "traverse" or "reload", then restore scroll position data
given event's relevant global object's navigable's active session history
entry.
Otherwise:
Let document be event's relevant global object's
associated Document.
If document's indicated part is null, then scroll to the beginning of the document given document. [CSSOMVIEW]
Otherwise, scroll to the fragment given document.
The NavigateEvent interface has its own
dedicated section, due to its complexity.
NavigationCurrentEntryChangeEvent interface[Exposed =Window ]
interface NavigationCurrentEntryChangeEvent : Event {
constructor (DOMString type , NavigationCurrentEntryChangeEventInit eventInitDict );
readonly attribute NavigationType ? navigationType ;
readonly attribute NavigationHistoryEntry from ;
};
dictionary NavigationCurrentEntryChangeEventInit : EventInit {
NavigationType ? navigationType = null ;
required NavigationHistoryEntry from ;
};event.navigationTypeReturns the type of navigation which caused the current entry to change, or null if the
change is due to navigation.updateCurrentEntry().
event.fromReturns the previous value of navigation.currentEntry, before the current entry
changed.
If navigationType
is null or "reload", then this value will be the
same as navigation.currentEntry. In that case,
the event signifies that the contents of the entry changed, even if we did not move to a new
entry or replace the current one.
The navigationType and from attributes must return the
values they were initialized to.
PopStateEvent interfaceSupport in all current engines.
Support in all current engines.
[Exposed =Window ]
interface PopStateEvent : Event {
constructor (DOMString type , optional PopStateEventInit eventInitDict = {});
readonly attribute any state ;
readonly attribute boolean hasUAVisualTransition ;
};
dictionary PopStateEventInit : EventInit {
any state = null ;
boolean hasUAVisualTransition = false ;
};event.stateSupport in all current engines.
Returns a copy of the information that was provided to pushState() or replaceState().
event.hasUAVisualTransitionReturns true if the user agent performed a visual transition for this navigation before dispatching this event. If true, the best user experience will be given if the author synchronously updates the DOM to the post-navigation state.
The state attribute must return the value it was
initialized to. It represents the context information for the event, or null, if the state
represented is the initial state of the Document.
The
hasUAVisualTransition attribute must return the value it was initialized to.
HashChangeEvent interfaceHashChangeEvent/HashChangeEvent
Support in all current engines.
Support in all current engines.
[Exposed =Window ]
interface HashChangeEvent : Event {
constructor (DOMString type , optional HashChangeEventInit eventInitDict = {});
readonly attribute USVString oldURL ;
readonly attribute USVString newURL ;
};
dictionary HashChangeEventInit : EventInit {
USVString oldURL = "";
USVString newURL = "";
};event.oldURLSupport in all current engines.
Returns the URL of the session history entry that was previously current.
event.newURLSupport in all current engines.
Returns the URL of the session history entry that is now current.
The oldURL attribute must return the value it was
initialized to. It represents context information for the event, specifically the URL of the
session history entry that was traversed from.
The newURL attribute must return the value it was
initialized to. It represents context information for the event, specifically the URL of the
session history entry that was traversed to.
PageSwapEvent interface[Exposed =Window ]
interface PageSwapEvent : Event {
constructor (DOMString type , optional PageSwapEventInit eventInitDict = {});
readonly attribute NavigationActivation activation ;
readonly attribute ViewTransition viewTransition ;
};
dictionary PageSwapEventInit : EventInit {
NavigationActivation ? activation = null ;
ViewTransition viewTransition = null ;
};event.activationA NavigationActivation object representing the destination and type of the
cross-document navigation. This would be null for cross-origin navigations.
event.activation.entryA NavigationHistoryEntry, representing the Document that is
about to become active.
event.activation.fromA NavigationHistoryEntry, equivalent to the value of the navigation.currentEntry property at the moment the
event is fired.
event.activation.navigationTypeOne of "push", "replace", "reload", or "traverse", indicating what type of navigation
that is about to result in a page swap.
event.viewTransitionReturns the ViewTransition object that represents an outbound cross-document view
transition, if such transition is active when the event is fired. Otherwise, returns null.
The activation and viewTransition attributes must return
the values they were initialized to.
PageRevealEvent interface[Exposed =Window ]
interface PageRevealEvent : Event {
constructor (DOMString type , optional PageRevealEventInit eventInitDict = {});
readonly attribute ViewTransition viewTransition ;
};
dictionary PageRevealEventInit : EventInit {
ViewTransition viewTransition = null ;
};event.viewTransitionReturns the ViewTransition object that represents an inbound cross-document view
transition, if such transition is active when the event is fired. Otherwise, returns null.
The viewTransition attribute must return the
value it was initialized to.
PageTransitionEvent interfacePageTransitionEvent/PageTransitionEvent
Support in all current engines.
Support in all current engines.
[Exposed =Window ]
interface PageTransitionEvent : Event {
constructor (DOMString type , optional PageTransitionEventInit eventInitDict = {});
readonly attribute boolean persisted ;
};
dictionary PageTransitionEventInit : EventInit {
boolean persisted = false ;
};event.persistedSupport in all current engines.
For the pageshow event, returns false if the page is
newly being loaded (and the load event will fire). Otherwise,
returns true.
For the pagehide event, returns false if the page is
going away for the last time. Otherwise, returns true, meaning that the page might be reused if
the user navigates back to this page (if the Document's salvageable state stays true).
Things that can cause the page to be unsalvageable include:
The user agent decided to not keep the Document alive in a session
history entry after unload
Having iframes that are not salvageable
Active WebSocket objects
The persisted attribute must return the value
it was initialized to. It represents the context information for the event.
To fire a page transition event named eventName at a Window
window with a boolean persisted, fire
an event named eventName at window, using
PageTransitionEvent, with the persisted attribute initialized to
persisted, the cancelable attribute
initialized to true, the bubbles attribute initialized to
true, and legacy target override flag set.
The values for cancelable and bubbles don't make any sense, since canceling the event does
nothing and it's not possible to bubble past the Window object. They are set to true
for historical reasons.
BeforeUnloadEvent interfaceSupport in all current engines.
[Exposed =Window ]
interface BeforeUnloadEvent : Event {
attribute DOMString returnValue ;
};There are no BeforeUnloadEvent-specific initialization methods.
The BeforeUnloadEvent interface is a legacy interface which allows checking
if unloading is canceled to be controlled not only by canceling the event, but by setting
the returnValue attribute to a value
besides the empty string. Authors should use the preventDefault() method, or other means of canceling
events, instead of using returnValue.
The returnValue attribute controls the process
of checking if unloading is canceled. When the event is created, the
attribute must be set to the empty string. On getting, it must return the last value it was set
to. On setting, the attribute must be set to the new value.
This attribute is a DOMString only for historical reasons.
Any value besides the empty string will be treated as a request to ask the user for
confirmation.
NotRestoredReasons interface[Exposed =Window ]
interface NotRestoredReasonDetails {
readonly attribute DOMString reason ;
[Default ] object toJSON ();
};
[Exposed =Window ]
interface NotRestoredReasons {
readonly attribute DOMString ? src ;
readonly attribute DOMString ? id ;
readonly attribute DOMString ? name ;
readonly attribute DOMString ? url ;
readonly attribute FrozenArray <NotRestoredReasonDetails >? reasons ;
readonly attribute FrozenArray <NotRestoredReasons >? children ;
[Default ] object toJSON ();
};notRestoredReasonDetails.reasonReturns a string that explains the reason that prevented the document from being served from back/forward cache. See the definition of bfcache blocking details for the possible string values.
notRestoredReasons.srcReturns the src attribute of the document's node
navigable's container if it is an iframe
element. This can be null if not set or if it is not an iframe element.
notRestoredReasons.idReturns the id attribute of the document's node
navigable's container if it is an iframe
element. This can be null if not set or if it is not an iframe element.
notRestoredReasons.nameReturns the name attribute of the document's
node navigable's container if it is an
iframe element. This can be null if not set or if it is not an iframe
element.
notRestoredReasons.urlReturns the document's URL, or null if the
document is in a cross-origin iframe. This is reported in addition to src because it is possible iframe
navigated since the original src was set.
notRestoredReasons.reasonsReturns an array of NotRestoredReasonDetails for the document. This is null
if the document is in a cross-origin iframe.
notRestoredReasons.childrenReturns an array of NotRestoredReasons that are for the document’s
children. This is null if the document is in a cross-origin iframe.
A NotRestoredReasonDetails object has a backing struct, a not restored reason details or null, initially null.
The reason getter steps are to return
this's backing struct's reason.
To create a NotRestoredReasonDetails object given a not restored reason details backingStruct and a
realm realm:
Let notRestoredReasonDetails be a new NotRestoredReasonDetails
object created in realm.
Set notRestoredReasonDetails's backing struct to backingStruct.
Return notRestoredReasonDetails.
A not restored reason details is a struct with the following items:
reason, a string, initially empty.
The reason is a string that represents the reason that prevented the page from being restored from back/forward cache. The string is one of the following:
fetch"Document was still ongoing and was canceled, so the page was not in a state that
could be stored in the back/forward cache.navigation-failure"Document errored, so storing the
resulting error document in the back/forward cache was
prevented.parser-aborted"Document never finished its initial HTML parsing, so storing the unfinished
document in the back/forward cache was prevented.websocket"WebSocket
connection was shut down, so the page was not in a state that could be stored in the back/forward cache. [WEBSOCKETS]lock"masked"Document has children that are in a cross-origin iframe, and
they prevented back/forward cache; or this Document
could not be back/forward cached for user agent-specific reasons, and
the user agent has chosen not to use one of the more specific reasons from the list of user-agent specific blocking reasons.
In addition to the list above, a user agent might choose to expose a reason that prevented the page from being restored from back/forward cache for user-agent specific blocking reasons. These are one of the following strings:
audio-capture"Document requested audio capture permission by using Media Capture and
Streams's getUserMedia() with audio. [MEDIASTREAM]background-work"Document requested background work by calling SyncManager's
register() method,
PeriodicSyncManager's register() method, or
BackgroundFetchManager's fetch() method.broadcastchannel-message"BroadcastChannel connection on the page received a message and message event was fired.idbversionchangeevent"Document had a pending IDBVersionChangeEvent while unloading. [INDEXEDDB]idledetector"Document had an active IdleDetector while unloading.keyboardlock"Keyboard's lock() method was
called.mediastream"MediaStreamTrack was in the live state upon unloading. [MEDIASTREAM]midi"Document requested a MIDI permission by calling navigator.requestMIDIAccess().modals"navigating"Document was not in a state that could be stored in back/forward cache.navigation-canceled"window.stop() and the page was not in a state to be stored in back/forward cache.non-trivial-browsing-context-group"Document had more than one
top-level browsing context.otpcredential"Document created an OTPCredential.outstanding-network-request"Document had
outstanding network requests and was not in a state that could be stored in back/forward cache.paymentrequest"Document had an active PaymentRequest while unloading. [PAYMENTREQUEST]pictureinpicturewindow"Document had an active PictureInPictureWindow while unloading. [PICTUREINPICTURE]plugins"Document contained plugins.request-method-not-get"Document was created from an HTTP request whose method was not `GET`.
[FETCH]response-auth-required"Document was created from an HTTP response that required HTTP
authentication.response-cache-control-no-store"Document was created from an HTTP response whose `Cache-Control` header included the "no-store" token. [HTTP]response-cache-control-no-cache"Document was created from an HTTP response whose `Cache-Control` header included the "no-cache" token. [HTTP]response-keep-alive"Document was created from an HTTP response that contained a `Keep-Alive` header.response-scheme-not-http-or-https"Document was created from a response whose URL's scheme was
not an HTTP(S) scheme. [FETCH]response-status-not-ok"Document was created from an HTTP response whose status was not an ok status.
[FETCH]rtc"RTCPeerConnection or
RTCDataChannel was shut down, so the page was not in a state that could be stored in
the back/forward cache. [WEBRTC]sensors"Document requested sensor
access.serviceworker-added"Document's service worker client started to be
controlled by a ServiceWorker while the page was
in back/forward cache. [SW]serviceworker-claimed"Document's service worker client's active service worker was claimed while
the page was in back/forward cache. [SW]serviceworker-postmessage"Document's service worker client's active service worker received a
message while the page was in back/forward cache. [SW]serviceworker-version-activated"Document's service worker client's active service worker's version was
activated while the page was in back/forward cache.
[SW]serviceworker-unregistered"Document's service worker client's active service worker's service
worker registration was unregistered while
the page was in back/forward cache. [SW]sharedworker"Document was in the owner set of a
SharedWorkerGlobalScope.smartcardconnection"Document had an active SmartCardConnection while unloading.speechrecognition"Document had an active SpeechRecognition while unloading.storageaccess"Document requested storage access permission by using the Storage Access
API.unload-listener"Document registered an event listener for the unload event.video-capture"Document requested video capture permission by using Media Capture and
Streams's getUserMedia() with video. [MEDIASTREAM]webhid"Document called the WebHID API's requestDevice() method.webshare"Document used the Web Share API's navigator.share() method.webtransport"WebTransport
connection was shut down, so the page was not in a state that could be stored in the back/forward cache. [WEBTRANSPORT]webxrdevice"Document created a XRSystem.A NotRestoredReasons object has a backing struct,
a not restored reasons or null, initially null.
A NotRestoredReasons object has a reasons array, a
FrozenArray< or null,
initially null.NotRestoredReasonDetails>
A NotRestoredReasons object has a children array, a
FrozenArray<NotRestoredReasons> or null, initially
null.
The src getter steps are to return
this's backing struct's src.
The id getter steps are to return
this's backing struct's id.
The name getter steps are to return
this's backing struct's name.
The url getter steps are:
If this's backing struct's URL is null, then return null.
Return this's backing struct's URL, serialized.
The reasons getter steps are to return
this's reasons array.
The children getter steps are to return
this's children array.
To create a NotRestoredReasons object given a not restored reasons backingStruct and a
realm realm:
Let notRestoredReasons be a new NotRestoredReasons object created
in realm.
Set notRestoredReasons's backing struct to backingStruct.
If backingStruct's reasons is null, set notRestoredReasons's reasons array to null.
Otherwise:
Let reasonsArray be an empty list.
For each reason of backingStruct's reasons:
Create a NotRestoredReasonDetails object given
reason and realm, and append
it to reasonsArray.
Set notRestoredReasons's reasons array to the result of creating a frozen array given reasonsArray.
If backingStruct's children is null, set notRestoredReasons's children array to null.
Otherwise:
Let childrenArray be an empty list.
For each child of backingStruct's children:
Create a NotRestoredReasons object given child
and realm and append it to
childrenArray.
Set notRestoredReasons's children array to the result of creating a frozen array given childrenArray.
Return notRestoredReasons.
A not restored reasons is a struct with the following items:
src, a string or null, initially null.
id, a string or null, initially null.
name, a string or null, initially null.
url, a URL or null, initially null.
reasons, null or a list of not restored reason details, initially null.
children, null or a list of not restored reasons, initially null.
A Document's not restored reasons is its node navigable's
active session history entry's document state's not restored reasons, if
Document's node navigable is a top-level traversable;
otherwise null.