LibJS: Implement Object.hasOwn() :^)

This is currently a TC39 Stage 2 proposal, but let's go for it! https://github.com/tc39/proposal-accessible-object-hasownproperty I wrote the C , @linusg found bugs and wrote the test.
SerenityOS · May 18, 2021 · 3ee092c · 3ee092c
1 parent 94569e5
commit 3ee092c
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diff --git a/Userland/Libraries/LibJS/Runtime/CommonPropertyNames.h b/Userland/Libraries/LibJS/Runtime/CommonPropertyNames.h
@@ -135,6 135,7 @@ namespace JS {
  P(globalThis) \
  P(groups) \
  P(has) \
  P(hasOwn) \
  P(hasOwnProperty) \
  P(hypot) \
  P(ignoreCase) \

diff --git a/Userland/Libraries/LibJS/Runtime/ObjectConstructor.cpp b/Userland/Libraries/LibJS/Runtime/ObjectConstructor.cpp
@@ -45,6 45,7 @@ void ObjectConstructor::initialize(GlobalObject& global_object)
  define_native_function(vm.names.values, values, 1, attr);
  define_native_function(vm.names.entries, entries, 1, attr);
  define_native_function(vm.names.create, create, 2, attr);
  define_native_function(vm.names.hasOwn, has_own, 2, attr);
 }
 
 ObjectConstructor::~ObjectConstructor()
@@ -310,4 311,15 @@ JS_DEFINE_NATIVE_FUNCTION(ObjectConstructor::create)
  return object;
 }
 
 JS_DEFINE_NATIVE_FUNCTION(ObjectConstructor::has_own)
 {
  auto* object = vm.argument(0).to_object(global_object);
  if (vm.exception())
  return {};
  auto string_or_symbol = StringOrSymbol::from_value(global_object, vm.argument(1));
  if (vm.exception())
  return {};
  return Value(object->has_own_property(string_or_symbol));
 }
 
 }
diff --git a/Userland/Libraries/LibJS/Runtime/ObjectConstructor.h b/Userland/Libraries/LibJS/Runtime/ObjectConstructor.h
@@ -42,6 42,7 @@ class ObjectConstructor final : public NativeFunction {
  JS_DECLARE_NATIVE_FUNCTION(values);
  JS_DECLARE_NATIVE_FUNCTION(entries);
  JS_DECLARE_NATIVE_FUNCTION(create);
  JS_DECLARE_NATIVE_FUNCTION(has_own);
 };
 
 }
diff --git a/Userland/Libraries/LibJS/Tests/builtins/Object/Object.hasOwn.js b/Userland/Libraries/LibJS/Tests/builtins/Object/Object.hasOwn.js
@@ -0,0 1,35 @@
 describe("basic functionality", () => {
  test("length", () => {
  expect(Object.hasOwn).toHaveLength(2);
  });
 
  test("returns true for existent own property", () => {
  const o = { foo: "bar" };
  expect(Object.hasOwn(o, "foo")).toBeTrue();
  });
 
  test("returns false for non-existent own property", () => {
  const o = {};
  expect(Object.hasOwn(o, "foo")).toBeFalse();
  });
 
  test("returns false for existent prototype chain property", () => {
  const o = {};
  Object.prototype.foo = "bar";
  expect(Object.hasOwn(o, "foo")).toBeFalse();
  });
 });
 
 describe("errors", () => {
  test("null argument", () => {
  expect(() => {
  Object.hasOwn(null);
  }).toThrowWithMessage(TypeError, "ToObject on null or undefined");
  });
 
  test("undefined argument", () => {
  expect(() => {
  Object.hasOwn(undefined);
  }).toThrowWithMessage(TypeError, "ToObject on null or undefined");
  });
 });