Easy rate limit with Promise.all and p-limit
Rate limiting API calls to an HTTP service doesn’t have to cumbersome and too complicated.
A simple way to achieve this (and that I use all the time) is to combine
Promise.all with an npm package called
p-limit is used to run multiple promise-returning & async functions with limited concurrency.
In the code below I want to make concurrent calls to an api (which can be an HTTP API, library call, pretty much anything that returns a
Promise), at most 5 at a time.
const pLimit = require('p-limit') const limit = pLimit(5) const urls = ['...', '...', ...] return Promise.all( urls.map(url => limit(() => request(url))) )
p-queue would be the perfect match for a rate limited queue implementation. Altough I find it more handy, easier to read and use
p-limit in combination with a simple
This altough applies only if you have a predefined / finite list of operations to run. If the operations are dynamic then you’ll probably go with