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Randomize Background Image

1. Above the DOCTYPE

Set up and array of filenames, which correspond to the file names of the images you are trying to randomize.

<?php
  $bg = array('bg-01.jpg', 'bg-02.jpg', 'bg-03.jpg', 'bg-04.jpg', 'bg-05.jpg', 'bg-06.jpg', 'bg-07.jpg' ); // array of filenames

  $i = rand(0, count($bg)-1); // generate random number size of the array
  $selectedBg = "$bg[$i]"; // set variable equal to which random filename was chosen
?>

1. CSS in the <head>

Normally you’d want to keep CSS out of the HTML, but we’ll just use it here to echo out the random file name we selected above.

<style type="text/css">
<!--
body{
background: url(images/<?php echo $selectedBg; ?>) no-repeat;
}
-->
</style>

12 Responses

  1. Antti says:

    You could probably do with even shorter code:

    <!–
    body{
    background: url(images/bg-0.jpg) no-repeat;
    }
    –>

    ..if there are under 10 images.

    • ??? I’m unsure about your method here. Where would you implement the php?

      • Antti says:

        Uh-oh, something seems to have gone wrong when I submitted that message. I meant:

        background: url(images/bg-0

        .jpg) no-repeat;

        This works of course only if there are <= 10 images.

        Let's see, if it works this time…

      • Yeah I assumed there was some inline PHP going on there. PHP tags get stripped from WordPress comments, so if you need to post them, put a space between like this < ?

      • Antti says:

        OK,

        so one more time (you probably already guess where I’m going here):

        background: url(images/bg-0.jpg) no-repeat;

        Like that!

  2. Michael says:

    Great snippet! How would I pull the images from a folder (and adds or subtracts from the list everytime the user uploads or deletes a photo from that directory)?

    mz

  3. I wrote this one for a client. Works well. It returns the path to a random image. In addition it won’t allow the same image to load twice consecutively .

  4. I guess I’m not allowed to post a hyperlink on my comment above. – Sorry about that.

  5. ryan says:

    this is not working for me for some reason…

  6. Kristofer says:

    Hey thanks for this php-code/css it works great now, just modified the css a little bit and it was exactly the code i needed! :) Cheers

  7. Ant says:

    And much better is give random class to body, and define backgrounds in main css file.

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