Array.prototype[@@iterator]() - JavaScript
the @@iterator method is part of the iterable protocol, that defines how to synchronously iterate over a sequence of values.
... the initial value of the @@iterator property is the same function object as the initial value of the values() property.
...oped variables in for loops // const and var could also be used for (let letter of iterator) { console.log(letter); } } // array logiterable(['a', 'b', 'c']); // a // b // c // string logiterable('abc'); // a // b // c logiterable(123); // 123 " is not an iterable object..." specifications specification ecmascript (ecma-262)the definition of 'array.prototype[@@iterator]()' in that specification.

Map.prototype[@@iterator]() - JavaScript
the initial value of the @@iterator property is the same function object as the initial value of the entries method.
... examples using [@@iterator]() const mymap = new map() mymap.set('0', 'foo') mymap.set(1, 'bar') mymap.set({}, 'baz') const mapiter = mymap[symbol.iterator]() console.log(mapiter.next().value) // ["0", "foo"] console.log(mapiter.next().value) // [1, "bar"] console.log(mapiter.next().value) // [object, "baz"] using [@@iterator]() with for..of const mymap = new map() mymap.set('0', 'foo') mymap.set(1, 'bar') mymap.set({}, 'baz') for (const entry of mymap...
...) { console.log(entry) } // ["0", "foo"] // [1, "bar"] // [{}, "baz"] for (const [key, value] of mymap) { console.log(`${key}: ${value}`) } // 0: foo // 1: bar // [object]: baz specifications specification ecmascript (ecma-262)the definition of 'map.prototype[@@iterator]()' in that specification.

Set.prototype[@@iterator]() - JavaScript
the initial value of the @@iterator property is the same function object as the initial value of the values property.
... examples using [@@iterator]() const myset = new set(); myset.add('0'); myset.add(1); myset.add({}); const setiter = myset[symbol.iterator](); console.log(setiter.next().value); // "0" console.log(setiter.next().value); // 1 console.log(setiter.next().value); // object using [@@iterator]() with for..of const myset = new set(); myset.add('0'); myset.add(1); myset.add({}); for (const v of myset) { console.log(v); } specifications specificati...
...on ecmascript (ecma-262)the definition of 'set.prototype[@@iterator]' in that specification.

String.prototype[@@iterator]() - JavaScript
the [@@iterator]() method returns a new iterator object that iterates over the code points of a string value, returning each code point as a string value.
... examples using [@@iterator]() var str = 'a\ud835\udc68'; var striter = str[symbol.iterator](); console.log(striter.next().value); // "a" console.log(striter.next().value); // "\ud835\udc68" using [@@iterator]() with for..of var str = 'a\ud835\udc68b\ud835\udc69c\ud835\udc6a'; for (var v of str) { console.log(v); } // "a" // "\ud835\udc68" // "b" // "\ud835\udc69" // "c" // "\ud835\udc6a" specifications specification ecmascript (ecma-262)the definition of 'string.prototype[@@ite...

TypedArray.prototype[@@iterator]() - JavaScript
the initial value of the @@iterator property is the same function object as the initial value of the values property.
...ve iteration var arr = new uint8array([10, 20, 30, 40, 50]); var earr = arr[symbol.iterator](); console.log(earr.next().value); // 10 console.log(earr.next().value); // 20 console.log(earr.next().value); // 30 console.log(earr.next().value); // 40 console.log(earr.next().value); // 50 specifications specification ecmascript (ecma-262)the definition of '%typedarray%.prototype[@@iterator]()' in that specification.

arguments[@@iterator]() - JavaScript
the initial value of the @@iterator property is the same function object as the initial value of the array.prototype.values property.

Iteration protocols - JavaScript
in order to be iterable, an object must implement the @@iterator method, meaning that the object (or one of the objects up its prototype chain) must have a property with a @@iterator key which is available via constant symbol.iterator: property value [symbol.iterator] a zero-argument function that returns an object, conforming to the iterator protocol.
... whenever an object needs to be iterated (such as at the beginning of a for...of loop), its @@iterator method is called with no arguments, and the returned iterator is used to obtain the values to be iterated.
... console.log(iterator.next()); // { value: "h", done: false } console.log(iterator.next()); // { value: "i", done: false } console.log(iterator.next()); // { value: undefined, done: true } some built-in constructs—such as the spread syntax—use the same iteration protocol under the hood: console.log([...somestring]); // ["h", "i"] you can redefine the iteration behavior by supplying our own @@iterator: // need to construct a string object explicitly to avoid auto-boxing let somestring = new string('hi'); somestring[symbol.iterator] = function () { return { // this is the iterator object, returning a single element (the string "bye") next: function () { return this._first ?
...And 3 more matches

Iterators and generators - JavaScript
in order to be iterable, an object must implement the @@iterator method.
... iterables which can iterate only once (such as generators) customarily return this from their @@iterator method, whereas iterables which can be iterated many times must return a new iterator on each invocation of @@iterator.
... function* makeiterator() { yield 1; yield 2; } const it = makeiterator(); for (const ititem of it) { console.log(ititem); } console.log(it[symbol.iterator]() === it) // true; // this example show us generator(iterator) is iterable object, // which has the @@iterator method return the it (itself), // and consequently, the it object can iterate only _once_.
... // if we change it's @@iterator method to a function/generator // which returns a new iterator/generator object, (it) // can iterate many times it[symbol.iterator] = function* () { yield 2; yield 1; }; user-defined iterables you can make your own iterables like this: const myiterable = { *[symbol.iterator]() { yield 1; yield 2; yield 3; } } for (let value of myiterable) { console.log(value); } // 1 // 2 // 3 or [...myiterable]; // [1, 2, 3] built-in iterables string, array, typedarray, map and set are all built-in iterables, because their prototype objects all have a symbol.iterator method.

Symbol.iterator - JavaScript
description whenever an object needs to be iterated (such as at the beginning of a for..of loop), its @@iterator method is called with no arguments, and the returned iterator is used to obtain the values to be iterated.
...the built-in types with a @@iterator method are: array.prototype[@@iterator]() typedarray.prototype[@@iterator]() string.prototype[@@iterator]() map.prototype[@@iterator]() set.prototype[@@iterator]() see also iteration protocols for more information.
...ield 3; }; [...myiterable] // [1, 2, 3] or iterables can be defined directly inside a class or object using a computed property: class foo { *[symbol.iterator] () { yield 1; yield 2; yield 3; } } const someobj = { *[symbol.iterator] () { yield 'a'; yield 'b'; } } [...new foo] // [ 1, 2, 3 ] [...someobj] // [ 'a', 'b' ] non-well-formed iterables if an iterable's @@iterator method does not return an iterator object, then it is a non-well-formed iterable.

Iterator - Archive of obsolete content
properties iterator.prototype[@@iterator] returns a function that returns iterator object.
.../ ["y", 20] console.log(iter.next()); // throws stopiteration iterating over properties of an object with legacy destructuring for-in statement var a = { x: 10, y: 20, }; for (var [name, value] in iterator(a)) { console.log(name, value); // x 10 // y 20 } iterating with for-of var a = { x: 10, y: 20, }; for (var [name, value] of iterator(a)) { // @@iterator is used console.log(name, value); // x 10 // y 20 } iterates over property name var a = { x: 10, y: 20, }; for (var name in iterator(a, true)) { console.log(name); // x // y } passing generator instance function* f() { yield 'a'; yield 'b'; } var g = f(); console.log(g == iterator(g)); // true for (var v in iterator(g))...

ECMAScript 2015 support in Mozilla - Archive of obsolete content
se symbol.iterator property (firefox 36) const (js 1.5, firefox 1.0) (es2015 compliance bug 950547 implemented in firefox 51) let (js 1.7, firefox 2) (es2015 compliance bug 950547 implemented in firefox 51) destructuring assignment (js 1.7, firefox 2) (es2015 compliance bug 1055984) statements for...of (firefox 13) works in terms of .iterator() and .next() (firefox 17) use "@@iterator" property (firefox 27) use symbol.iterator property (firefox 36) functions rest parameters (firefox 15) default parameters (firefox 15) parameters without defaults after default parameters (firefox 26) destructured parameters with default value assignment (firefox 41) arrow functions (firefox 22) generator function (firefox 26) yield (firefox 26) yield* (fir...
...efox 27) arguments[@@iterator] (firefox 46) other features binary and octal numeric literals (firefox 25) template strings (firefox 34) object initializer: shorthand property names (firefox 33) object initializer: computed property names (firefox 34) object initializer: shorthand method names (firefox 34) ...

JS_FS
for example, use js_sym_fn(iterator, ...) to define an @@iterator method.
... (in builds without es6 symbols, it defines a method with the string id "@@iterator".) see an example in the jsapi user guide.

Bytecode Descriptions
jsop::calliter is used for implicit calls to @@iterator methods, to ensure error messages are formatted with jsmsg_not_iterable ("x is not iterable") rather than jsmsg_not_function ("x[symbol.iterator] is not a function").

WebIDL bindings
this is specified by writing [alias="@@iterator"].

MediaKeyStatusMap - Web APIs
mediakeystatusmap.[@@iterator]() read only returns a new iterator object containing an array of [key, value] for each element in the status map, in insertion order.