THE WORLD'S LARGEST WEB DEVELOPER SITE
×

JS Tutorial

JS HOME JS Introduction JS Where To JS Output JS Syntax JS Statements JS Comments JS Variables JS Operators JS Arithmetic JS Assignment JS Data Types JS Functions JS Objects JS Scope JS Events JS Strings JS String Methods JS Numbers JS Number Methods JS Math JS Random JS Dates JS Date Formats JS Date Methods JS Arrays JS Array Methods JS Array Sort JS Booleans JS Comparisons JS Conditions JS Switch JS Loop For JS Loop While JS Break JS Type Conversion JS Bitwise JS RegExp JS Errors JS Debugging JS Hoisting JS Strict Mode JS Style Guide JS Best Practices JS Mistakes JS Performance JS Reserved Words JS Versions JS JSON

JS Forms

JS Forms Forms API

JS Objects

Object Definitions Object Properties Object Methods Object Prototypes

JS Functions

Function Definitions Function Parameters Function Invocation Function Closures

JS HTML DOM

DOM Intro DOM Methods DOM Document DOM Elements DOM HTML DOM CSS DOM Animations DOM Events DOM Event Listener DOM Navigation DOM Nodes DOM Collections DOM Node Lists

JS Browser BOM

JS Window JS Screen JS Location JS History JS Navigator JS Popup Alert JS Timing JS Cookies

JS AJAX

AJAX Intro AJAX XMLHttp AJAX Request AJAX Response AJAX XML File AJAX PHP AJAX ASP AJAX Database AJAX Applications AJAX Examples

JS JSON

JSON Intro JSON Syntax JSON vs XML JSON Data Types JSON Objects JSON Arrays JSON Parse JSON Stringify JSON PHP JSON HTML JSON JSONP

JS Examples

JS Examples JS HTML DOM JS HTML Input JS HTML Objects JS HTML Events JS Browser JS Quiz JS Certificate

JS References

JavaScript Objects HTML DOM Objects


JavaScript Timing Events


1
2
3
4
5
6
7
8
9
10
11
12

JavaScript can be executed in time-intervals.

This is called timing events.


Timing Events

The window object allows execution of code at specified time intervals.

These time intervals are called timing events.

The two key methods to use with JavaScript are:

  • setTimeout(function, milliseconds)
    Executes a function, after waiting a specified number of milliseconds.
  • setInterval(function, milliseconds)
    Same as setTimeout(), but repeats the execution of the function continuously.

The setTimeout() and setInterval() are both methods of the HTML DOM Window object.


The setTimeout() Method

window.setTimeout(function, milliseconds);

The window.setTimeout() method can be written without the window prefix.

The first parameter is a function to be executed.

The second parameter indicates the number of milliseconds before execution.

Example

Click a button. Wait 3 seconds, and the page will alert "Hello":

<button onclick="setTimeout(myFunction, 3000)">Try it</button>

<script>
function myFunction() {
    alert('Hello');
}
</script>
Try it Yourself »


How to Stop the Execution?

The clearTimeout() method stops the execution of the function specified in setTimeout().

window.clearTimeout(timeoutVariable)

The window.clearTimeout() method can be written without the window prefix.

The clearTimeout() method uses the variable returned from setTimeout():

myVar = setTimeout(function, milliseconds);
clearTimeout(myVar);

If the function has not already been executed, you can stop the execution by calling the clearTimeout() method:

Example

Same example as above, but with an added "Stop" button:

<button onclick="myVar = setTimeout(myFunction, 3000)">Try it</button>

<button onclick="clearTimeout(myVar)">Stop it</button>
Try it Yourself »

The setInterval() Method

The setInterval() method repeats a given function at every given time-interval.

window.setInterval(function, milliseconds);

The window.setInterval() method can be written without the window prefix.

The first parameter is the function to be executed.

The second parameter indicates the length of the time-interval between each execution.

This example executes a function called "myTimer" once every second (like a digital watch).

Example

Display the current time:

var myVar = setInterval(myTimer, 1000);

function myTimer() {
    var d = new Date();
    document.getElementById("demo").innerHTML = d.toLocaleTimeString();
}
Try it Yourself »

There are 1000 milliseconds in one second.


How to Stop the Execution?

The clearInterval() method stops the executions of the function specified in the setInterval() method.

window.clearInterval(timerVariable)

The window.clearInterval() method can be written without the window prefix.

The clearInterval() method uses the variable returned from setInterval():

myVar = setInterval(function, milliseconds);
clearInterval(myVar);

Example

Same example as above, but we have added a "Stop time" button:

<p id="demo"></p>

<button onclick="clearInterval(myVar)">Stop time</button>

<script>
var myVar = setInterval(myTimer, 1000);
function myTimer() {
    var d = new Date();
    document.getElementById("demo").innerHTML = d.toLocaleTimeString();
}
</script>
Try it Yourself »

More Examples

Another simple timing

A clock created with a timing event