setTimeout()
In this chapter you will learn:
Time out timer
setTimeout() executes code after a specified amount of time.
setTimeout()method accepts two arguments:- the code to execute
- the number of time (in milliseconds) to wait.
The first argument can be either a string containing JavaScript code or a function.
The following code runs an document.writeln after 1 second:
<!DOCTYPE HTML> <!-- j av a 2 s . co m-->
<html>
<body>
<script type="text/javascript">
setTimeout(function() {
document.writeln("Hello world!");
},
1000
);
</script>
</body>
</html>
Stop a time out timer
setTimeout() returns a numeric ID for the timeout.
The ID can be used to cancel the timeout.
To cancel a pending timeout, use the clearTimeout()
method and pass in the timeout ID:
<!DOCTYPE HTML> <!--from j a v a 2s .c om-->
<html>
<body>
<script type="text/javascript">
var timeoutId = setTimeout(function() {
document.writeln("Hello world!");
}, 1000);
clearTimeout(timeoutId);
</script>
</body>
</html>
Time out for a value
The following code set the timeout according to a value:
<!DOCTYPE HTML> <!-- jav a 2 s. c om-->
<html>
<body>
<script type="text/javascript">
var num = 0;
var max = 10;
function incrementNumber() {
document.writeln(num++);
//if the max has not been reached,
//set another timeout
if (num < max) {
setTimeout(incrementNumber, 500);
} else {
document.writeln("Done");
}
}
setTimeout(incrementNumber, 500);
</script>
</body>
</html>
Next chapter...
What you will learn in the next chapter:
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