# p-limit [](https://travis-ci.org/sindresorhus/p-limit) > Run multiple promise-returning & async functions with limited concurrency ## Install ``` $ npm install p-limit ``` ## Usage ```js const pLimit = require('p-limit'); const limit = pLimit(1); const input = [ limit(() => fetchSomething('foo')), limit(() => fetchSomething('bar')), limit(() => doSomething()) ]; (async () => { // Only one promise is run at once const result = await Promise.all(input); console.log(result); })(); ``` ## API ### pLimit(concurrency) Returns a `limit` function. #### concurrency Type: `number`<br> Minimum: `1` Concurrency limit. ### limit(fn, ...args) Returns the promise returned by calling `fn(...args)`. #### fn Type: `Function` Promise-returning/async function. #### args Any arguments to pass through to `fn`. Support for passing arguments on to the `fn` is provided in order to be able to avoid creating unnecessary closures. You probably don't need this optimization unless you're pushing a *lot* of functions. ### limit.activeCount The number of promises that are currently running. ### limit.pendingCount The number of promises that are waiting to run (i.e. their internal `fn` was not called yet). ## FAQ ### How is this different from the [`p-queue`](https://github.com/sindresorhus/p-queue) package? This package is only about limiting the number of concurrent executions, while `p-queue` is a fully featured queue implementation with lots of different options, introspection, and ability to pause and clear the queue. ## Related - [p-queue](https://github.com/sindresorhus/p-queue) - Promise queue with concurrency control - [p-throttle](https://github.com/sindresorhus/p-throttle) - Throttle promise-returning & async functions - [p-debounce](https://github.com/sindresorhus/p-debounce) - Debounce promise-returning & async functions - [p-all](https://github.com/sindresorhus/p-all) - Run promise-returning & async functions concurrently with optional limited concurrency - [More…](https://github.com/sindresorhus/promise-fun) ## License MIT © [Sindre Sorhus](https://sindresorhus.com)