JavaScript Tutorial >> JavaScript SetTimeOut.

In JavaScript with setTimeOut function, we have to remember that JavaScript execution is *not* stopped. So even though we are setting an event to take place in the future, our script continues to run. So our while loop will keep executing and changing the images, there is no pause.

There are two ways of creating time delays in JavaScript. The first is more simple and will simply wait for a specified amount of time before executing a JavaScript function. The second does the same but will repeatedly execute the JavaScript function.

Note, most browsers have a minimum delay length of between 25 and 75 ms. If a shorter delay is specified, the actual delay will be the minimum delay length. Even with higher numbers, the delay is never perfect. Most web browsers will take slightly longer than the time we ask for, typically just a few milliseconds error. Some may correct their errors over time with interval timers. Also note, setting many timers with short delays on one page will cause the web browser to become slow and somewhat unresponsive. Three or four timers is usually the reliable limit.

The first method uses a window method called setTimeout() in JavaScript. The setTimeOut() method waits for a specified number of milliseconds then executes the specified code. The code can either be a direct reference to a JavaScript function, or it can be a string that will be evaluated as if it contained source code.

<img id="banner">

<SCRIPT LANGUAGE="JavaScript">

<!--

var banner=0;



function changingBanner()

{

  if(banner<5){

    var img ="";

    img = "../images/banner" + banner + ".jpg";

    document.getElementById("banner").src= img;

    document.getElementById("banner").alt= 

    "JavaScript Tutorial, JavaScript SetTimeOut()";

    banner++;

    if(banner==5){

      banner=0;

    }

  }

//this JavaScript setTimeOut() function will recall the

//changingBanner() after one second

setTimeout("changingBanner()", 3000);

}



changingBanner();

-->

</SCRIPT>

►setTimeout() and clearTimeout() Example in JavaScript
►Making a delay with window.setTimeout()
►Pausing JavaScript For, Do and While Loops using setTimeout() Example
►Example of stop watch using window.setTimeout()