When I went looking for a built-in “sleep()” function in Javascript, I quickly learned that it does not exist. This is surprising considering that “sleep()” is in all other languages that I have used. To get around this javascript shortcoming, I decided to create my own sleep function. The result is a function that loops internally until the number of seconds passed is greater than the argument value, “naptime”.

Initial tests of “sleep()” were successful, however, I soon discovered that most browsers will interrupt “sleep()” and show a “Slow/Busy script” dialog message whenever the “naptime” argument is greater than 10 seconds (7 seconds in IE). Trying to work around this problem was too much effort, so I left the script as is. If you use this function, I recommend a “naptime” of less than 10 seconds so your site visitors won’t encounter this “slow script” dialog message.

Below are some examples of the javascript “sleep()” function. Just click on a link below to start sleeping for the preset amount of seconds shown.

[Sleep for 3 Seconds]   [Sleep for 5 Seconds]   [Sleep for 10 Seconds]   [Sleep for 20 Seconds]

Here is the script source:

//A javascript sleep function by Helene D.
jQuery.fn.sleep = function (naptime) {
  		var loop = false;
		var maxiterations = 9000000;
  		var now = new Date();
  		var timestarted = now.getTime();
		naptime=naptime+0;	//convert to number
		if (naptime >0 ) {
			loop = true;
			if (naptime < 100) {	//convert to microseconds
				naptime=(naptime*1000);
				naptime=naptime-940;	//estim. script exec time
			}
		}
		var i=0;
  		while(loop) {
			i++;
  			now = new Date();
  			timenow = now.getTime();
  			if(timenow - timestarted > naptime) {
  				loop = false;
			} else if (i > maxiterations) { //no infinite loops
				loop = false;
			}
  		}
		return $(this);
  }

The usage is: sleep(seconds);. You can also chain it in jQuery like this: $(this).sleep(seconds).replace(wakeUp);

If you are not a jQuery user, you can convert this function to plain javascript by replacing jQuery.fn.sleep = function(naptime) with function sleep(naptime) and remove the return $(this) line near the bottom of the script.