promise-me-later

A minimal, vanilla JS library to throttle/rate-limit fetch, API calls and other promise returning functions ♻️

When to use

When you need to limit any promise returning function call rate but still want each call to happen over time. For example, a good use case for this is to limit calling APIs from fetch in browser or node-fetch in node environment.

Usage

As a node module

npm i promise-me-later

import promiseMeLater from 'promise-me-later';
 
// any promise returning function
const delay = () => new Promise((resolve, reject) => {
    console.log('Resolving promise');
    setTimeout(() => {
        resolve();
        console.log('Promise resolved');
    }, 1000);	// resolves the promise after 1 second
})
 
// returns a rate limited function
const limit = promiseMeLater(delay, 1, 2000);	// call at max once in 2 seconds
 
// also try this with fetch call, since it also returns a promise
const limitFetch = promiseMeLater(fetch, 2, 1000);
/* will only be called at max twice in 1 second
 * as soon as a promise is resloved, another will be picked
 * from the queue and invoked
 *  Now you can use `limitFetch` instead of `fetch`
 * and all your `fetch` calls will be rate limited */

As a UMD

Motivation

I was looking for a simple way to rate limit fetch calls, the caveat being that each call should happen (unlike throttling).

For best results, listen to Promise by Slash 🎸 and Chris ❤️