Widely available Supported across all major browsers. Safe to use in production.

Generators

The Generator object is returned by a generator function and it conforms to both the iterable protocol and the iterator protocol.

Generator is a subclass of the Iterator class.

Language core

Browser support

Feature Desktop Mobile
Chrome
Edge
Firefox
Safari
Chrome Android
Safari iOS
Generator
39
13
26
10
39
10
Generator.next

The next() method of Generator instances returns an object with two properties done and value. You can also provide a parameter to the next method to send a value to the generator.
39
13
26
10
39
10
Generator.return

The return() method of Generator instances acts as if a return statement is inserted in the generator's body at the current suspended position, which finishes the generator and allows the generator to perform any cleanup tasks when combined with a try...finally block.
50
13
38
10
50
10
Generator.throw

The throw() method of Generator instances acts as if a throw statement is inserted in the generator's body at the current suspended position, which informs the generator of an error condition and allows it to handle the error, or perform cleanup and close itself.
39
13
26
10
39
10
Other
javascript.builtins.GeneratorFunction

The GeneratorFunction object provides methods for generator functions. In JavaScript, every generator function is actually a GeneratorFunction object.
39
13
26
10
39
10
Built-in object
GeneratorFunction.GeneratorFunction

The GeneratorFunction() constructor creates GeneratorFunction objects.
39
13
26
10
39
10
Other
javascript.operators.generator_function

`function*` expression
49
12
26
10
49
10
Operator
trailing comma

Trailing comma in parameters
58
79
52
10
58
10
Other
javascript.operators.yield

The yield operator is used to pause and resume a generator function.
39
12
26
10
39
10
javascript.operators.yield_star

`yield*`
39
12
27
10
39
10
javascript.statements.generator_function

`function*` statement
39
13
26
10
39
10
Statement
IteratorResult object

`IteratorResult` object instead of throwing
49
13
29
10
49
10
not constructable with new

Not constructable with `new` (ES2016)
50
13
43
10
50
10
trailing comma in parameters

Trailing comma in parameters
58
14
52
10
58
10
1+Supported (version) Not supported ※Has note Sub-feature descriptions sourced from MDN Web Docs (CC BY-SA 2.5)
Notes 2 item(s)
Implementation note
  • Starting with Firefox 33, the parsing of the `yield` expression has been updated to conform with the ES2015 specification.
  • Starting with Firefox 29, an `IteratorResult` object returned for completed generator function.
Notes 1 item(s)
Implementation note
  • Starting with Firefox 33, the parsing of the `yield` expression has been updated to conform with the ES2015 specification.

Syntax

JAVASCRIPT 
function* fibonacci() {
  let [a, b] = [0, 1];
  while (true) {
    yield a;
    [a, b] = [b, a + b];
  }
}

const fib = fibonacci();
fib.next().value; // 0
fib.next().value; // 1
fib.next().value; // 1
fib.next().value; // 2

Live demo

steprungenerator

Processing one timeStop, one timebetween per and to next. Value generatesimul-tion.. with yield

PreviewFullscreen

nonenumbershi-kens

none to continueshi-kens from, main taiming in value 1 getout..

PreviewFullscreen

de-ta. Sequentialprocessing

big de-tasett array, generator Usesplit to processing..

PreviewFullscreen

Use cases

  • Using Generators

    The Generator object is returned by a generator function and it conforms to both the iterable protocol and the iterator protocol.

Cautions

  • No specific concerns. Stable across all major browsers.

Accessibility

  • When updating the DOM dynamically, announce important changes to assistive technology with aria-live regions.

Related links