JavaScript setInterval() Function Examples

Sam Deering

The JavaScript setInterval function can be used to automate a task using a regular time based trigger. Just to be clear, setInterval() is a native JavaScript function.

This function is very similar to the jQuery setTimeout() Function.

Basic setInterval() Example

setInterval(function() {
      // Do something every 5 seconds
}, 5000);

Tips: If your changing images dynamically load variables from a PHP script you will need to add some sort of random number to the script so that it forces a refresh in all browsers. You can do this by using the following code to generate a random number.

$(document).ready(function()
{
    var refreshId = setInterval( function() 
    {
        var r = (-0.5)+(Math.random()*(1000.99));
        $('#img-container').load('images/gallery/best/random.php?'+r);
    }, 5000);
});

Tips: You might also have to use the ajax method instead of load, to prevent the AJAX request to be cached.
Tips: Alternatively, you could stick header(“Cache-Control: no-cache, must-revalidate”); towards the top of your random.php file to prevent the browser from caching.

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  • Chris

    Just an FYI to save cionfusion for people later on…

    RE:

    The jQuery setInterval function

    setInterval isn’t a jQuery function it is a native function of Javascript!

  • http://blog.outsourcingnepal.com Outsourcing Nepal

    just a clean example… but as already said setinterval is javascript native function

  • Greg

    Yeah, seriously, setTimeout() and setInterval() have nothing to do with jQuery… They are pure vanilla JavaScript, available long before jQuery was even a thought.

    Also, fix the formatting on your second example. Line 3 should be indented another level.

    • jquery4u

      @Greg – thanks for the constructive comments. Code indentation fixed up.
      @Chris, Nepal – noted.

  • Elwood

    Still Helpful

  • Nic Johnson

    Hi there, thanks for the code, but setInterval and setTimeout are not jQuery functions, they’re just plain old JavaScript. Still useful though.

  • Mike

    I think we need one more comment explaining that this isn’t jQuery.

    • http://jquery4u.com/ jQuery4u

      done, added a link to W3.

  • 416

    ohhhhh i think setInterval is not a jquery function LOL since noone mentioned it……….

    • http://jquery4u.com/ jQuery4u

      :)

  • Prabu Govindsamy

    the setinterval() is getting called when app is minimized in ios simulator why is that so ?