Cannot set property 'src' of null

Question

I am trying to rotate an image using javascript and I was trying some code I found on adobes website that does what I was looking for. When I run it it gives me the error: Unca

Answer 1

You need to place this code after your dom gets ready. i.e inside $(document).ready() or on window.onload. as:

window.onload=function(){
(function () {
    var rotator = document.getElementById('rotator');  // change to match image ID
    var imageDir = 'images/';                          // change to match images folder
    var delayInSeconds = 5;                            // set number of seconds delay
    // list image names
    var images = ['image2.jpg', 'image3.jpg', 'image4.jpg', 'image1.jpg'];

    // don't change below this line
    var num = 0;
    var changeImage = function () {
        var len = images.length;
        rotator.src = imageDir + images[num++];
        if (num == len) {
            num = 0;
        }
    };
    setInterval(changeImage, delayInSeconds * 1000);
})();

If you place that code inside anynomous function inside head (as you did), then it will not be able to load that image element from Dom because Dom would not be fully loaded at that time.