How do I make my background change images automatically every 15 seconds? JavaScript? jQuery?

I know this sounds simple and I searched up and down the web for a script but cant find anything. I just want my backgrounds to change every 15 seconds or so a开发者_如何学Pythonutomatically. (like a photo slide show but as a background.) My style sheet is controls the bg image in the body tag. Thanks for the help.

With setInterval, you can call an arbitrary function in, well, intervals:

(function() {
    var curImgId = 0;
    var numberOfImages = 42; // Change this to the number of background images
    window.setInterval(function() {
        $('body').css('background-image','url(/background' + curImgId + '.jpg)');
        curImgId = (curImgId + 1) % numberOfImages;
    }, 15 * 1000);
})();

Simple enough to do with setInterval:

var currentIndex = 1;
var totalCount = 21;

setInterval(function() {
    if (currentIndex > totalCount)
        currentIndex = 1;

    $(body).css('background-image', 'url(/bg' + currentIndex++ + '.jpg)');
}, 15000);

<script src="http://codeorigin.jquery.com/jquery-2.0.3.min.js"></script>
<script style="text/javascript">
    (function () {
        var curImgId = 0;
        var numberOfImages = 5; // Change this to the number of background images
        window.setInterval(function() {
            $('body').css('background','url("'+ curImgId +'.jpg")');// set the image path here
            curImgId = (curImgId + 1) % numberOfImages;
        }, 15 * 1000);
    })();

</script>