The [Symbol.asyncDispose]() method of AsyncIterator instances implements the async disposable protocol and allows it to be disposed when used with await using. It calls and awaits the return() method of this, if it exists.

Syntax

asyncIterator[Symbol.asyncDispose]()

Parameters

None.

Return value

None (undefined).

Examples

Declaring an async iterator with await using

The Symbol.asyncDispose method is intended to be automatically called in an await using declaration. This is useful if you have an async iterator that you manually iterate over by calling its next() method; if you iterate it with for await...of or something similar, then error handling and cleanup is done automatically.

async function* generateNumbers() {
  try {
    yield 1;
    yield 2;
    yield 3;
  } finally {
    console.log("Cleaning up");
  }
}

async function doSomething() {
  await using numbers = generateNumbers();
  const res1 = await numbers.next();
  // Not iterating the rest of the numbers
  // Before the function exits, the async iterator is disposed
  // Logs "Cleaning up"
}

doSomething();

Specifications

Browser compatibility

See also

• Polyfill of AsyncIterator.prototype[Symbol.asyncDispose] in core-js
• JavaScript resource management
• Symbol.asyncDispose
• await using