Random Backstretch image

gistfile1.html

<script>
    // Create an array of images that you'd like to use
    var images = [
        'image1.jpg'
      , 'image2.jpg'
      , 'image3.jpg'
    ];
    
    // Get a random number between 0 and the number of images
    var randomNumber = Math.floor( Math.random() * images.length );

    // Use the random number to load a random image
    $.backstretch(images[randomNumber]);
</script>