JavaScript Standard Style

One Style to Rule Them All

No decisions to make. No .eslintrc, .jshintrc, or .jscsrc files to manage. It just works.

This module saves you (and others!) time in two ways:

• No configuration. The easiest way to enforce consistent style in your project. Just drop it in.
• Catch style errors before they're submitted in PRs. Saves precious code review time by eliminating back-and-forth between maintainer and contributor.

Install

npm install standard

Rules

• 2 spaces – for indentation
• Single quotes for strings – except to avoid escaping
• No unused variables – this one catches tons of bugs!
• No semicolons – It's fine. Really!
• Never start a line with ( or [
  • This is the only gotcha with omitting semicolons – automatically checked for you!
  • More details
• Space after keywords if (condition) { ... }
• Space after function name function name (arg) { ... }
• Name the context variable self – var self = this
  • Accidental window.self usage is dissallowed (happens when var self = this is omitted)
• Always use === instead of == – but obj == null is allowed to check null || undefined.
• Always handle the node.js err function parameter
• Always prefix browser globals with window – except document and navigator are okay
  • Prevents accidental use of poorly-named browser globals like open, length, event, and name.
• And more goodness – give standard a try today!

To get a better idea, take a look at a sample file written in JavaScript Standard Style, or check out some of the repositories that use standard.

Badge

Use this in one of your projects? Include one of these badges in your readme to let people know that your code is using the standard style.

[![js-standard-style](https://cdn.rawgit.com/feross/standard/master/badge.svg)](https://github.com/feross/standard)

[![js-standard-style](https://img.shields.io/badge/code style-standard-brightgreen.svg?style=flat)](https://github.com/feross/standard)

Usage

The easiest way to use JavaScript Standard Style to check your code is to install it globally as a Node command line program. To do so, simply run the following command in your terminal (flag -g installs standard globally on your system, omit it if you want to install in the current working directory):

npm install standard -g

After you've done that you should be able to use the standard program. The simplest use case would be checking the style of all JavaScript files in the current working directory:

$ standard
Error: Use JavaScript Standard Style
  lib/torrent.js:950:11: Expected '===' and instead saw '=='.

You can optionally pass in a directory using the glob pattern:

$ standard src/util/**/*.js

Note: by default standard will look for all files matching the patterns: **/*.js, **/*.jsx.

Editor plugins

First, install standard. Then, install the appropriate plugin for your editor:

• Sublime Text - Install Package Control, SublimeLinter, and SublimeLinter-contrib-standard.
• Atom - Install Linter and linter-js-standard.
• Vim - Install Syntastic and add let g:syntastic_javascript_checkers = ['standard'] to your .vimrc.
• Emacs - Install Flycheck and check out the manual to learn how to enable it in your projects.

What you might do if you're clever

1. Add it to package.json

{
  "name": "my-cool-package",
  "devDependencies": {
    "standard": "^3.0.0"
  },
  "scripts": {
    "test": "standard && node my-tests.js"
  }
}

1. Check style automatically when you run npm test

$ npm test
Error: Use JavaScript Standard Style
  lib/torrent.js:950:11: Expected '===' and instead saw '=='.

1. Never give style feedback on a pull request again!

FAQ

Why would I use JavaScript Standard Style?

The beauty of JavaScript Standard Style is that it's simple. No one wants to maintain multiple hundred-line style configuration files for every module/project they work on. Enough of this madness!

This module saves you time in two ways:

• No configuration. The easiest way to enforce consistent style in your project. Just drop it in.
• Catch style errors before they're submitted in PRs. Saves precious code review time by eliminating back-and-forth between maintainer and contributor.

Adopting standard style means ranking the importance of code clarity and community conventions higher than personal style. This might not make sense for 100% of projects and development cultures, however open source can be a hostile place for newbies. Setting up clear, automated contributor expectations makes a project healthier.

I disagree with rule X, can you change it?

No. The the whole point of standard is to avoid bikeshedding about style. There are lots of debates online about tabs vs. spaces, etc. that will never be resolved. These debates just distract from getting stuff done. At the end of the day you have to 'just pick something', and that's the whole philosophy of standard -- its a bunch of sensible 'just pick something' opinions. Hopefully, users see the value in that over defending their own opinions.

But this isn't a real web standard!

Of course it's not! The style laid out here is not affiliated with any official web standards groups, which is why this repo is called feross/standard and not ECMA/standard.

The word "standard" has more meanings than just "web standard" :-) For example:

• This module helps hold our code to a high standard of quality.
• This module ensures that new contributors follow some basic style standards.

Is there an automatic formatter?

Yes! Just run standard --format filename.js. This uses Max Ogden's automatic formatter standard-format, which can automatically fix most code issues.

While most issues can be fixed, some, like not handling errors in node-style callbacks, must be fixed manually.

How do I ignore files?

The paths node_modules/**, *.min.js, bundle.js, coverage/**, hidden files/folders (beginning with .), and all patterns in a project's root .gitignore file are automatically excluded when looking for .js files to check.

Sometimes you need to ignore additional folders or specific minfied files. To do that, add a standard.ignore property to package.json:

"standard": {
  "ignore": [
    "**/out/",
    "/lib/select2/",
    "/lib/ckeditor/",
    "tmp.js"
  ]
}

How do I hide a certain warning?

In rare cases, you'll need to break a rule and hide the warning generated by standard.

JavaScript Standard Style uses eslint under-the-hood and you can hide warnings as you normally would if you used eslint directly.

To get verbose output (so you can find the particular rule name to ignore), run:

$ standard --verbose
Error: Use JavaScript Standard Style
  routes/error.js:20:36: 'file' was used before it was defined. (no-use-before-define)

Disable all rules on a specific line:

file = 'I know what I am doing' // eslint-disable-line

Or, disable only the "no-use-before-define" rule:

file = 'I know what I am doing' // eslint-disable-line no-use-before-define

Or, disable the "no-use-before-define" rule for multiple lines:

/*eslint-disable no-use-before-define */
// offending code here...
// offending code here...
// offending code here...
/*eslint-enable no-use-before-define */

I use a library that pollutes the global namespace. How do I prevent "variable is not defined" errors?

Some packages (e.g. mocha) put their functions (e.g. describe, it) on the global object (poor form!). Since these functions are not defined or required anywhere in your code, standard will warn that you're using a variable that is not defined (usually, this rule is really useful for catching typos!). But we want to disable it for these global variables.

To let standard (as well as humans reading your code) know that certain variables are global in your code, add this to the top of your file:

/* global myVar1, myVar2 */

If you have hundreds of files, adding comments to every file can be tedious. In these cases, you can add this to package.json:

{
  "standard": {
    "global": [ "myVar1", "myVar2" ]
  }
}

Can I use a custom JS parser for bleeding-edge ES6 or ES7 support?

standard supports custom JS parsers. To use a custom parser, install it from npm (example: npm install babel-eslint) and add this to your package.json:

{
  "standard": {
    "parser": "babel-eslint"
  }
}

Can you make rule X configurable?

No. Use eslint and this shareable config if you want to configure hundreds of options individually.

Pro tip: Just use standard and move on. There are actual real problems that you could spend your time solving! :P

What about Web Workers?

Web workers have a magic global variable called self. In regular JS files, standard won't let you use self directly, as it wants to prevent accidental use of window.self. But standard has no way of knowing when you are in a worker and therefore does not know when to allow usage of self directly.

Until we figure out a better solution, we recommend adding this to the top of workers:

/* global self */

This lets standard (as well as humans reading your code) know that self is a global in web worker code.

Is there a Git pre-commit hook for standard?

Funny you should ask!

#!/bin/sh 
# Ensure all javascript files staged for commit pass standard code style 
git diff --name-only --cached --relative | grep '\.js$' | xargs standard
exit $?

Alternatively, overcommit is a Git hook manager that includes support for running standard as a Git pre-commit hook. To enable this, add the following to your .overcommit.yml file:

PreCommit:
  Standard:
    enabled: true

I want to hack on standard. What packages should I know about?

• eslint
• standard
  • eslint-config-standard
  • eslint-config-standard-react
• semistandard
  • eslint-config-semistandard
• standard-format
• standard-engine

There are also many editor plugins.

License

MIT. Copyright (c) Feross Aboukhadijeh.