batchasync.js

Like calling map() and resolving with Promise.all(), but handling a bounded number of items at any given time.

Want to read about it?

• Batching async requests in < 50 lines of VanillaJS

Install

npm install --save batchasync

Usage

// Browsers
var batchAsync = window.batchAsync;

// Node
var batchAsync = require('batchasync').batchAsync;

var batchSize = 4;
var things = ['apples', 'bananas', 'pears'];

function doStuff() {
    // ... go fetch things
}

batchAsync(batchSize, things, doStuff).then(function(results) {
    // all results, in order, just like Promise.all()
    console.log(results[0]);
});

A note on undefined

Returning undefined will cause an exception to be thrown, and the Promise to be rejected.

This is on purpose - because undefined is indistinguishable from a skipped Promise.

Return null instead.

Example (bad):

function doStuff(thing) {
    // Oops! forgot to return
    request('https://searchallthe.pictures/api/' + thing);
}

Example (good):

function doStuff(thing) {
    return request('https://searchallthe.pictures/api/' + thing);
}

Example (good):

function doStuff(thing) {
    return null;
}