Chain an AbortController to multiple AbortSignals


Chain multiple signals into one controller: if any of the signals aborts, the controller will be aborted. This is particularly useful since most APIs only accept a _single_ AbortSignal input (fetch(), axios, the AWS SDK, etc).

Works with browsers, NodeJS (16+), and spec-compliant polyfills.

Usage

At a minimum, you must pass one or more AbortSignals. However, the controller is optional: if a controller is _not_ passed in, one will be created and returned.

``typescript
import { chainAbortController } from "abortcontroller-chain";

// use your own controller
chainAbortController(controller, signal1, signal2, signal3);

// auto-create the controller
const controller = chainAbortController(signal1, signal2, signal3);
`

Why

Say you're passing an AbortSignal into a long-running piece of code so you can end early if needed:

`typescript
async function pollSomething(signal: AbortSignal) {
while (!signal.aborted) {
// keep polling until the signal says stop
}
}
`

But wait! You want to make an HTTP request with a _deadline_ of 10 seconds:

`typescript
const TEN_SECONDS = 10 * 1000; // ms
async function pollSomething(signal: AbortSignal) {
while (!signal.aborted) {
// abort after 500ms
const abortController = new AbortController();
setTimeout(() => abortController.abort(), TEN_SECONDS);

// do the fetch...
const result = await fetch("/something-something", {
// wait, this doesn't take into account the signal
// passed to pollSomething()
signal: abortController.signal,
});

/ ... /
}
}
`

Wouldn't it be great if the fetch-specific abortController could be aborted by the outer signal? That's easy with the abortcontroller-chain package:

`typescript
import { chainAbortController } from "abortcontroller-chain";

const TEN_SECONDS = 10 * 1000; // ms
async function pollSomething(signal: AbortSignal) {
while (!signal.aborted) {
const abortController = new AbortController();
chainAbortController(abortController, signal);
setTimeout(() => abortController.abort(), TEN_SECONDS);

// do the fetch...
const result = await fetch("/something-something", {
// hooray! both signals are now respected
signal: abortController.signal,
});

/ ... /
}
}
`

You can further simplify the creation:

`typescript
const abortController = chainAbortController(signal);
setTimeout(() => abortController.abort(), TEN_SECONDS);
``