p-timeout

Timeout a promise after a specified amount of time

[!NOTE] You may want to use AbortSignal.timeout() instead. Learn more.

Install

npm install p-timeout

Usage

import {setTimeout} from 'node:timers/promises';
import pTimeout from 'p-timeout';

const delayedPromise = setTimeout(200);

await pTimeout(delayedPromise, {
	milliseconds: 50,
});
//=> [TimeoutError: Promise timed out after 50 milliseconds]

API

pTimeout(input, options)

Returns a decorated input that times out after milliseconds time. It has a .clear() method that clears the timeout.

If you pass in a cancelable promise, specifically a promise with a .cancel() method, that method will be called when the pTimeout promise times out.

input

Type: Promise

Promise to decorate.

options

Type: object

milliseconds

Type: number

Milliseconds before timing out.

Passing Infinity will cause it to never time out.

message

Type: string | Error | false
Default: 'Promise timed out after 50 milliseconds'

Specify a custom error message or error to throw when it times out:

• message: 'too slow' will throw TimeoutError('too slow')
• message: new MyCustomError('it’s over 9000') will throw the same error instance
• message: false will make the promise resolve with undefined instead of rejecting

If you do a custom error, it's recommended to sub-class TimeoutError:

import {TimeoutError} from 'p-timeout';

class MyCustomError extends TimeoutError {
	name = "MyCustomError";
}

fallback

Type: Function

Do something other than rejecting with an error on timeout.

You could for example retry:

import {setTimeout} from 'node:timers/promises';
import pTimeout from 'p-timeout';

const delayedPromise = () => setTimeout(200);

await pTimeout(delayedPromise(), {
	milliseconds: 50,
	fallback: () => {
		return pTimeout(delayedPromise(), {milliseconds: 300});
	},
});

customTimers

Type: object with function properties setTimeout and clearTimeout

Custom implementations for the setTimeout and clearTimeout functions.

Useful for testing purposes, in particular to work around sinon.useFakeTimers().

Example:

import {setTimeout} from 'node:timers/promises';
import pTimeout from 'p-timeout';

const originalSetTimeout = setTimeout;
const originalClearTimeout = clearTimeout;

sinon.useFakeTimers();

// Use `pTimeout` without being affected by `sinon.useFakeTimers()`:
await pTimeout(doSomething(), {
	milliseconds: 2000,
	customTimers: {
		setTimeout: originalSetTimeout,
		clearTimeout: originalClearTimeout
	}
});

signal

Type: AbortSignal

You can abort the promise using AbortController.

Requires Node.js 16 or later.

import pTimeout from 'p-timeout';
import delay from 'delay';

const delayedPromise = delay(3000);

const abortController = new AbortController();

setTimeout(() => {
	abortController.abort();
}, 100);

await pTimeout(delayedPromise, {
	milliseconds: 2000,
	signal: abortController.signal
});

TimeoutError

Exposed for instance checking and sub-classing.

Related

• delay - Delay a promise a specified amount of time
• p-min-delay - Delay a promise a minimum amount of time
• p-retry - Retry a promise-returning function
• More…

AbortSignal

Modern alternative to p-timeout

Asynchronous functions like fetch can accept an AbortSignal, which can be conveniently created with AbortSignal.timeout().

The advantage over p-timeout is that the promise-generating function (like fetch) is actually notified that the user is no longer expecting an answer, so it can interrupt its work and free resources.

// Call API, timeout after 5 seconds
const response = await fetch('./my-api', {signal: AbortSignal.timeout(5000)});

async function buildWall(signal) {
	for (const brick of bricks) {
		signal.throwIfAborted();
		// Or: if (signal.aborted) { return; }

		await layBrick();
	}
}

// Stop long work after 60 seconds
await buildWall(AbortSignal.timeout(60_000))

You can also combine multiple signals, like when you have a timeout and an AbortController triggered with a “Cancel” button click. You can use the upcoming AbortSignal.any() helper or abort-utils.