// 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]);
});

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

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

function doStuff(thing) {
    return null;
}