p-limit
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    4.0.0 • Public • Published

    p-limit

    Run multiple promise-returning & async functions with limited concurrency

    Install

    $ npm install p-limit
    

    Usage

    import pLimit from 'p-limit';
    
    const limit = pLimit(1);
    
    const input = [
    	limit(() => fetchSomething('foo')),
    	limit(() => fetchSomething('bar')),
    	limit(() => doSomething())
    ];
    
    // 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
    Minimum: 1
    Default: Infinity

    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).

    limit.clearQueue()

    Discard pending promises that are waiting to run.

    This might be useful if you want to teardown the queue at the end of your program's lifecycle or discard any function calls referencing an intermediary state of your app.

    Note: This does not cancel promises that are already running.

    FAQ

    How is this different from the 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 the queue.

    Related

    • p-queue - Promise queue with concurrency control
    • p-throttle - Throttle promise-returning & async functions
    • p-debounce - Debounce promise-returning & async functions
    • p-all - Run promise-returning & async functions concurrently with optional limited concurrency
    • More…

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    Install

    npm i p-limit

    DownloadsWeekly Downloads

    49,281,093

    Version

    4.0.0

    License

    MIT

    Unpacked Size

    7.79 kB

    Total Files

    5

    Last publish

    Collaborators

    • sindresorhus