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 += 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().