AsyncDisposableStack.prototype.defer()

The defer() method of AsyncDisposableStack instances takes a callback function to be called and awaited when the stack is disposed.

See DisposableStack.prototype.defer() for general information about the defer() method.

Syntax

js
defer(onDispose)

Parameters

onDispose

A function that will be called when the stack is disposed. The function receives no arguments and can return a promise which gets awaited.

Return value

None (undefined).

Exceptions

TypeError

Thrown if onDispose is not a function.

ReferenceError

Thrown if the stack is already disposed.

Examples

undefined

Using defer()

One use case of defer() is to do something unrelated to resource freeing during scope exit, such as logging a message.

js
async function doSomething() {
  await using disposer = new AsyncDisposableStack();
  disposer.defer(async () => {
    await fs.writeFile("log.txt", "All resources freed successfully");
  });
  // Other code that claims and frees more data
}

Specifications

See also