Chillout.js - Reduce JavaScript CPU Usage by Asynchronous Iteration.

Written by Kevin Liew on 31 Aug 2016
51,710 Views • Javascript

For Loop is a very common iteration statement for an action repeatedly for a certain number of times, for example, looping through an array of data.

I faced something like this before. I had to loop through a large number of data, thousands of data in an array, in Chrome it was doing fine however in IE, I got a warning saying "Unresponsive Script". I can either stop the script or continue and wait until it's finished.

Chillout.js is here to avoid that issue by adding delay if the processing is heavy to main the CPU stability. It will iterate without delay if processing is fast. Therefore, it will realize friendly processing for your machine. It can execute JavaScript without "Warning: Unresponsive Script" alert in the browser.

The Comparison

Here is the comparison of coding and CPU usage for For Statement and Chillout.js

For Statement

var time =;
for (var i = 0; i < 1000; i++) {
var processingTime = - time;



var time =;
chillout.repeat(1000, function(i) {
}).then(function() {
  var processingTime = - time;

As you can see, the difference is quite obvious, you can read the detailed result from the dev github page.


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