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ECMAScript 2015 objects initializers

var obj = {
  property( parameters ) {},
  *generator( parameters ) {},
  async property( parameters ) {},
  async* generator( parameters ) {},

  // with computed keys:
  [property]( parameters ) {},
  *[generator]( parameters ) {},
  async [property]( parameters ) {},

  // compare getter/setter syntax:
  get property() {},
  set property(value) {}
};

ECMAScript 2015 getter setter

var obj = {
  foo: function () {
    /* code */
  },
  bar: function () {
    /* code */
  },
};

var obj = {
  foo() {
    /* code */
  },
  bar() {
    /* code */
  },
};

Generator method

* * g(){} g *(){}
yield SyntaxErrorAlways use yield in conjunction with the asterisk (*).

// Using a named property
var obj2 = {
  g: function* () {
    var index = 0;
    while (true) yield index++;
  },
};

// The same object using shorthand syntax
var obj2 = {
  *g() {
    var index = 0;
    while (true) yield index++;
  },
};

var it = obj2.g();
console.log(it.next().value); // 0
console.log(it.next().value); // 1

Async

// Using a named property
var obj3 = {
  f: async function () {
    await some_promise;
  },
};

// The same object using shorthand syntax
var obj3 = {
  async f() {
    await some_promise;
  },
};

Async generator methods

Generator methods can also be async.

var obj4 = {
  f: async function* () {
    yield 1;
    yield 2;
    yield 3;
  },
};

// The same object using shorthand syntax
var obj4 = {
  async *f() {
    yield 1;
    yield 2;
    yield 3;
  },
};

Method definitions are not constructable

All method definitions are not constructors and will throw a TypeError if you try to instantiate them.

var obj = {
  method() {},
};
new obj.method(); // TypeError: obj.method is not a constructor

var obj = {
  *g() {},
};
new obj.g(); // TypeError: obj.g is not a constructor (changed in ES2016)

Simple test case

var obj = {
  a: "foo",
  b() {
    return this.a;
  },
};
console.log(obj.b()); // "foo"

Computed property names

The shorthand syntax also supports computed property names.

var bar = {
  foo0: function () {
    return 0;
  },
  foo1() {
    return 1;
  },
  ["foo" + 2]() {
    return 2;
  },
};

console.log(bar.foo0()); // 0
console.log(bar.foo1()); // 1
console.log(bar.foo2()); // 2

Specification
ECMAScript 2027 LanguageSpecification # sec-method-definitions

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