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:

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 = 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. and shared by all AsyncGeneratorFunction instances.

AsyncGeneratorFunction..constructor: The constructor function that created the instance object. For AsyncGeneratorFunction instances, the initial value is the AsyncGeneratorFunction constructor.
AsyncGeneratorFunction..: All async generator functions share the same property, which is AsyncGenerator.. Each async generator function created with the async function* syntax or the AsyncGeneratorFunction() constructor also has its own property, whose is AsyncGeneratorFunction... When the async generator function is called, its property becomes the of the returned async generator object.
AsyncGeneratorFunction.[Symbol.toStringTag]: The initial value of the [Symbol.toStringTag] property is the string "AsyncGeneratorFunction". This property is used in Object..toString().

These properties are own properties of each AsyncGeneratorFunction instance.

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

Instance methods

Inherits instance methods from its parent Function.

Specifications

Specification
ECMAScript® 2026 Language Specification # sec-asyncgeneratorfunction-objects