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JavaScript setInterval() Function Examples

By Sam Deering

JavaScript

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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.

Sam Deering has 15+ years of programming and website development experience. He was a website consultant at Console, ABC News, Flight Centre, Sapient Nitro, and the QLD Government and runs a tech blog with over 1 million views per month. Currently, Sam is the Founder of Crypto News, Australia.

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