setTimeout

Summary

Evaluates an expression after a specified number of milliseconds has elapsed.

Syntax

var timeoutId = window.setTimeout(/* see parameter list */);

Parameters

expression

Data-type: String

Variant that specifies the function pointer or string that indicates the code to be executed when the specified interval has elapsed.

msec

Data-type: String

Integer that specifies the number of milliseconds.

language

Data-type: String

(Optional)

String that specifies one of the following values:

Return Value

Returns an object of type NumberNumber

Integer

Integer. Returns an identifier that cancels the evaluation with the clearTimeout method.

Examples

The following example uses the setTimeout method to evaluate a simple expression after one second has elapsed.

window.setTimeout("alert('Hello, world')", 1000);

The following example uses the setTimeout method to evaluate a slightly more complex expression after one second has elapsed.

var sMsg = "Hello, world";
window.setTimeout("alert(" + sMsg + ")", 1000);

This example uses the setTimeout method to hide a input type=button object after three seconds. If the user clicks the Count Down button and then counts to three, the Now You See Me button disappears.

<script type="text/javascript">
function fnHide(oToHide){
   window.setTimeout("fnHide2(" + oToHide.id + ")", 3000);
}
function fnHide2(sID){
   var o = eval(sID);
   o.style.display="none";
}
</script>
<input type="button" value="Count Down"
    id="oHideButton" onclick="fnHide(this)">

This example uses a function pointer to pass the data. In this case, the data is stored in a global variable because it cannot be passed directly. In the preceding example, the ID of the button is passed as a parameter to the function invoked by the setTimeout method. This is possible only when a string is passed as the first argument.

<script type="text/javascript">
var g_oToHide = null;
function fnHide(oToHide){
    g_oToHide = oToHide;
    window.setTimeout(fnHide2, 3000);
}
function fnHide2(sID){
    if (g_oToHide) {
       g_oToHide.style.display="none";
    }
}
</script>
<input type="button" value="Now you see me ..."
    id="oHideButton" onclick="fnHide(this)">

View live example

Notes

Remarks

The specified expression or function is evaluated once. For repeated evaluation, use the setInterval method. When you use the setTimeout method with Introduction to DHTML Behaviors, the value of expression should be a function pointer to call a function within the HTML Component (HTC) file or a string to call a function in the primary document.

Note In Windows Internet Explorer, you cannot pass arguments to the callback function directly; however, you can simulate passing arguments by creating an anonymous closure function that references variables within scope of the call to setInterval or setTimeout. In versions earlier than Microsoft Internet Explorer 5, the first argument of setTimeout must be a string. Evaluation of the string is deferred until the specified interval elapses. As of Internet Explorer 5, the first argument of setTimeout can be a string or a function pointer.

Reliability & timeout clamping

This API does not guarantee that timers will run exactly on schedule. Delays due to CPU load, other tasks, etc, are to be expected. Additionally a setTimeout or setInterval call has a minimum interval of of 4 ms, as specified by the HTML4 spec.

Generally all browsers implement this timeout “clamp” to 4 ms, although some browsers also clamp to a higher value when the window is not focused. For instance, the minimum timeout for a setInterval call can be up to a second in Chrome when the tab is inactive.

Attributions

Mozilla Developer Network : [setTimeout Article]
Microsoft Developer Network: [setTimeout Method Article]