sleep() in JavaScript

March 24th, 2008. Tagged: JavaScript, performance

PHP has a sleep() function, but JavaScript doesn't. Well, this is because it's useless, you might say, and you'll be right. But for simulating heavy processing and for misc performance measurements, it could be useful. So here's how you can go about creating a sleep() in JavaScript.

The code

function sleep(milliseconds) {
  var start = new Date().getTime();
  for (var i = 0; i < 1e7; i++) {
    if ((new Date().getTime() - start) > milliseconds){


Sleep for 1 second (1000 milliseconds):

console.log(new Date());
console.log(new Date());

Result in Firebug's console:


Tell your friends about this post on Facebook and Twitter

Sorry, comments disabled and hidden due to excessive spam.

Meanwhile, hit me up on twitter @stoyanstefanov