call-parallel

Call an array of functions in parallel (allow set the limit number of tasks executing at the same time)

ES6 and async/await syntax support (Node 7.6.0+).

Usage

parallel(tasks)

Run the tasks array of functions in parallel with a maximum of limit tasks executing at the same time (if passed), without waiting until the previous function has completed. If any of the functions pass an error to it's callback, the main is immediately fulfilled with the value of the error. Once the tasks have completed, the results are passed to the result array.

Note that the tasks are not executed in batches, so there is no guarantee that the first limit tasks will complete before any others are started.

It is also possible to use an object instead of an array. Each property will be run as a function and the results will be passed to the final object instead of an array. This can be a more readable way of handling the results.

Arguments

• tasks - An array or object containing functions to run. Each function is passed a callback(err, result) which it must call on completion with an error err (which can be null) and an optional result value.
• limit - The maximum number of tasks to run at any time. Default 0 – no limit.

Return

Promise, which will be fulfilled, when all the functions have completed. It's gets an object with err property and results array (or object) containing all the result arguments passed to the task callbacks.

Example

'use strict';

const parallel = require('call-parallel');

(async() => {
  // the results array will equal ['one','two'] even though
  // the second function had a shorter timeout
  console.log(await parallel([
    callback => setTimeout(() => callback(null, 'one'), 500),
    callback => setTimeout(() => callback(null, 'two'), 100)
  ]));
})();

This module is basically equivalent to run-parallel, but it's not support async/await.

See also

• run-auto
• run-parallel-limit
• run-series
• run-waterfall

License

MIT. Copyright (c) Anton Kenikh.