Preloading images in javascript

chris (2004-06-09 12:22:51)
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0 replies
It's wise to preload images when a site loads to enable smooth transitions on rollovers and other events. In this example I have three images - one of a button and two more of the button in a 'hover' state and 'click' state. 
<script language="javascript">
        var button = new Image();
        var buttonhover = new Image();
        var buttonclick = new Image();
                                                                                                                             
        // drag the images up and plop then on local disc
        button.src="images/button_arrow_.gif";
        buttonhover.src="images/button_arrow_hover.gif";
        buttonclick.src="images/button_arrow_pressed.gif";
        doPreload();
        function doPreload(){
           var the_images = new Array('images/button.gif','images/button_hover.gif','images/button_pressed.gif');
           preloadImages(the_images);
        }
        function preloadImages(the_images_array) {
           for(var loop = 0; loop < the_images_array.length; loop++){
                var an_image = new Image();
                an_image.src = the_images_array[loop];
           }
        }
</script>

These images have now been loaded up to the client and cached locally for quick access.

christo
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