Verify that all images are loaded in `$(window).load()` function before proceeding

Question

I am adding a number of large images for a slide-show to a page, but I want to start loading these images only when the normal part of the page is completely loaded (including the images).

To do that, I am adding the images in the $(window).load() function:

var slide_total = 20;

$(window).load(function() {

    for (i = 2; i <= slide_total; i++)
    {
        content = '<li><img src="/images/header' + ((i < 10) ? '0' : '') + i + '.jpg" width="960" height="314"></li>';
        $("#slideshow li:last-child").after(content);
    }

    slide_interval = setInterval( "slideSwitch()", slide_duration );

});

The slide-show slideSwitch() should start when all images are loaded completely, but as it is now, it starts the moment the elements are added to the DOM.

I cannot move the loop to the document.ready function as I don´t want the slide-show to interfere with the loading of the normal images.

How can I check whether all images are loaded before setting the interval?

Answer 1

Try this:

// get the total number of images inserted in the DOM
var imgCount = $('#slideshow img').length;

// initialize a counter which increments whenever an image finishes loading
var loadCounter = 0;

// bind to the images' load event
$("#slideshow li img").load(function() {

    // increment the load counter
    loadCounter++;

    // once the load counter equals the total number of images
    // set off the fancy stuff
    if(loadCounter == imgCount) {
        slide_interval = setInterval( "slideSwitch()", slide_duration );
    }
}).each(function() {

    // trigger the load event in case the image has been cached by the browser
    if(this.complete) $(this).trigger('load');
});