AsyncGeneratorFunction

Baseline Widely available

This feature is well established and works across many devices and browser versions. It’s been available across browsers since January 2020.

The AsyncGeneratorFunction object provides methods for async generator functions. In JavaScript, every async generator function is actually an AsyncGeneratorFunction object.

Note that AsyncGeneratorFunction is not a global object. It can be obtained with the following code:

js
const AsyncGeneratorFunction = async function* () {}.constructor;

AsyncGeneratorFunction is a subclass of Function.

Try it

const AsyncGeneratorFunction = async function* () {}.constructor;

const foo = new AsyncGeneratorFunction(`
  yield await Promise.resolve('a');
  yield await Promise.resolve('b');
  yield await Promise.resolve('c');
`);

let str = "";

async function generate() {
  for await (const val of foo()) {
    str += val;
  }
  console.log(str);
}

generate();
// Expected output: "abc"

Constructor

AsyncGeneratorFunction()

Creates a new AsyncGeneratorFunction object.

Instance properties

Also inherits instance properties from its parent Function.

These properties are defined on AsyncGeneratorFunction.prototype and shared by all AsyncGeneratorFunction instances.

AsyncGeneratorFunction.prototype.constructor

The constructor function that created the instance object. For AsyncGeneratorFunction instances, the initial value is the AsyncGeneratorFunction constructor.

AsyncGeneratorFunction.prototype.prototype

All async generator functions share the same prototype property, which is AsyncGenerator.prototype. Each async generator function created with the async function* syntax or the AsyncGeneratorFunction() constructor also has its own prototype property, whose prototype is AsyncGeneratorFunction.prototype.prototype. When the async generator function is called, its prototype property becomes the prototype of the returned async generator object.

AsyncGeneratorFunction.prototype[Symbol.toStringTag]

The initial value of the [Symbol.toStringTag] property is the string "AsyncGeneratorFunction". This property is used in Object.prototype.toString().

These properties are own properties of each AsyncGeneratorFunction instance.

prototype

Used when the function is used as a constructor with the new operator. It will become the new object's prototype.

Instance methods

Inherits instance methods from its parent Function.

Specifications

Specification
ECMAScript® 2027 Language Specification
# sec-asyncgeneratorfunction-objects

Browser compatibility

desktop mobile server
Chrome
Edge
Firefox
Opera
Safari
Chrome Android
Firefox for Android
Opera Android
Safari on iOS
Samsung Internet
WebView Android
WebView on iOS
Bun
Deno
Node.js
AsyncGeneratorFunction
Chrome – Full support
Chrome 63 (Release date: 2017-12-06)
footnote Full support
Edge – Full support
Edge 79 (Release date: 2020-01-15)
footnote Full support
Firefox – Full support
Firefox 55 (Release date: 2017-08-08)
footnote Full support
Opera – Full support
Opera 50 (Release date: 2018-01-04)
footnote Full support
Safari – Full support
Safari 12 (Release date: 2018-09-17)
footnote Full support
Chrome Android – Full support
Chrome Android 63 (Release date: 2017-12-05)
footnote Full support
Firefox for Android – Full support
Firefox for Android 55 (Release date: 2017-08-08)
footnote Full support
Opera Android – Full support
Opera Android 46 (Release date: 2018-05-14)
footnote Full support
Safari on iOS – Full support
Safari on iOS 12 (Release date: 2018-09-17)
footnote Full support
Samsung Internet – Full support
Samsung Internet 8 (Release date: 2018-07-18)
footnote Full support
WebView Android – Full support
WebView Android 63 (Release date: 2017-12-05)
footnote Full support
WebView on iOS – Full support
WebView on iOS 12 (Release date: 2018-09-17)
footnote Full support
Bun – Full support
Bun 1 (Release date: 2023-09-08)
footnote Full support
Deno – Full support
Deno 1 (Release date: 2020-05-13)
footnote Full support
Node.js – Full support
Node.js 10 (Release date: 2018-04-24)
footnote Full support
AsyncGeneratorFunction() constructor
Chrome – Full support
Chrome 63 (Release date: 2017-12-06)
footnote Full support
Edge – Full support
Edge 79 (Release date: 2020-01-15)
footnote Full support
Firefox – Full support
Firefox 55 (Release date: 2017-08-08)
footnote Full support
Opera – Full support
Opera 50 (Release date: 2018-01-04)
footnote Full support
Safari – Full support
Safari 12 (Release date: 2018-09-17)
footnote Full support
Chrome Android – Full support
Chrome Android 63 (Release date: 2017-12-05)
footnote Full support
Firefox for Android – Full support
Firefox for Android 55 (Release date: 2017-08-08)
footnote Full support
Opera Android – Full support
Opera Android 46 (Release date: 2018-05-14)
footnote Full support
Safari on iOS – Full support
Safari on iOS 12 (Release date: 2018-09-17)
footnote Full support
Samsung Internet – Full support
Samsung Internet 8 (Release date: 2018-07-18)
footnote Full support
WebView Android – Full support
WebView Android 63 (Release date: 2017-12-05)
footnote Full support
WebView on iOS – Full support
WebView on iOS 12 (Release date: 2018-09-17)
footnote Full support
Bun – Full support
Bun 1 (Release date: 2023-09-08)
footnote Full support
Deno – Full support
Deno 1 (Release date: 2020-05-13)
footnote Full support
Node.js – Full support
Node.js 10 (Release date: 2018-04-24)
footnote Full support
Requires arguments to be TrustedScript instance when trusted types are enforced
Chrome – No support
Chrome
footnote No support
Edge – No support
Edge
footnote No support
Firefox – Preview support
Firefox Nightly
footnote Preview browser support
Opera – No support
Opera
footnote No support
Safari – Full support
Safari 26 (Release date: 2025-09-15)
footnote Full support
Chrome Android – No support
Chrome Android
footnote No support
Firefox for Android – No support
Firefox for Android
footnote No support
Opera Android – No support
Opera Android
footnote No support
Safari on iOS – Full support
Safari on iOS 26 (Release date: 2025-09-15)
footnote Full support
Samsung Internet – No support
Samsung Internet
footnote No support
WebView Android – No support
WebView Android
footnote No support
WebView on iOS – Full support
WebView on iOS 26 (Release date: 2025-09-15)
footnote Full support
Bun – No support
Bun
footnote No support
Deno – No support
Deno
footnote No support
Node.js – No support
Node.js
footnote No support

Legend

Tip: you can click/tap on a cell for more information.

Full support
Full support
In development. Supported in a pre-release version.
In development. Supported in a pre-release version.
No support
No support

See also