javascript - jQuery .load() not firing on images (probably caching?)

Question

I have some pretty basic jQuery code:

...
$(this).find('img').load(function(){
   loadedImages++;
   if(loadedImages == $this.find('img').length){
...

However, thats not firing consistently. It fires if i do a hard refresh or close my browser, but a normal refresh, or just hitting the same URL twice at any time without erasing the cache makes the .load() never fire.

Any ideas on how to fix this?

Answer 1

I think this has been discussed before. It’s not the caching per se that is the problem but the timing: the images may already have been loaded by the time the event handler is attached (so it never gets fired). This may also occur if no caching happens, for example in a multithreaded browser on a very fast connection. Fortunately, there is a property .complete that you can use:

var load_handler = function() {
    loadedImages++;
    …
}
$(this).find('img').filter(function() {
    return this.complete;
}).each(load_handler).end().load(load_handler);

You can also create your own event attach function:

jQuery.fn.extend({
    ensureLoad: function(handler) {
        return this.each(function() {
            if(this.complete) {
                handler.call(this);
            } else {
                $(this).load(handler);
            }
        });
    }
});

And then call it as follows:

$(this).find('img').ensureLoad(function(){
    loadedImages++;
    if(loadedImages == $this.find('img').length){
    …
});