Javascript

Javascript – Sleep Function

11 Comments

There is no sleep()/wait() function in Javascript. The setTimeout() is not exactly a sleep()/wait() function as it behaves like creating another thread for the scheduled task.

By Google, i got a manual sleep()/wait() function. Try the following code.

*Update @ 2011-07-22: This function drains CPU usage and may throw error in IE. Use with extreme caution. Thanks SmartCoder for pointing out the issue. =)

<html>
  <head>
    <script type="text/javascript">
      /**
       * Delay for a number of milliseconds
       */
      function sleep(delay) {
        var start = new Date().getTime();
        while (new Date().getTime() < start + delay);
      }
    </script>
  </head>
  <body>
    <h1>Eureka!</h1>
      <script type="text/javascript">
        alert("Wait for 5 seconds.");
        sleep(5000)
        alert("5 seconds passed.");
      </script>
  </body>
</html>

 

Done =)

Reference: JavaScript Sleep Function

11 thoughts on “Javascript – Sleep Function”

  1. This is not good practice, as it will drain cpu usage, and cause IE to throw errors if longer than 5 seconds.

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  2. Here’s a possible alternative that may work in some cases:

    function Sleep(){return(function(){alert("I'm awake");});} // Does nothing.	
var goToSleep = Sleep(); // Create the object.
alert("Go to sleep");
setTimeout(goToSleep, 5000); // Go to sleep for n milliseconds.

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  3. Hi,

    If you need sleep function – you can send sync request to server …
    function sleep(milliseconds) {
    //code here for you SYNC request to server /*asp.net or php*/
    }

    it’s works,browser block all events until http response.

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  4. Test

    var begin;

function test()
{
	try
	{
		var seconds = 3;
		test1();
		setTimeout("alert('check')", (seconds * 500));
		//wait(seconds);
		//sleep(seconds);
		delay(seconds, "test2");
		test2();
	}
	catch(e)
	{
		if(e.number != -9999)
		{
			alert(e.description);
		}
	}
}

function test1()
{
	begin = (new Date()).getTime();
	alert("begin " + begin);
}

function test2()
{
	var end = (new Date()).getTime();
	alert("end " + end + " =&gt; " + ((end - begin) / 1000));
}

function delay(time, fnReturn)
{
	var fnOnError = window.onerror;
	window.onerror = function(){return false;};

	setTimeout("returnDelay('" + fnReturn + "', '" + fnOnError + "')", time * 1000);
	throw {"description" : "Delay stop processing",
	       "number" : -9999};
}

function returnDelay(fnReturn, fnOnError)
{
	window.onerror = fnOnError;
	eval(fnReturn + "()");
}

function sleep(time, isBegin)
{
	var deep = 10;

	if(isBegin == null || isBegin)
	{
		time *= deep;
	}

	if(time &gt; 0)
	{
		var delay = 1000 / deep;
		var begin = (new Date()).getTime();
		while((new Date()).getTime() &lt; begin + delay){void(0);}
		sleep(--time, false);
	}
}

function wait(time)
{
	time *= 1000;
	var begin = (new Date()).getTime();
	while((new Date()).getTime() &lt; begin + time){void(0);}
}

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