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#waitForImages#

Copyright (c) 2011-2016 Alexander Dickson @alexdickson

Licensed under the MIT licenses.

http://alexanderdickson.com

##Overview##

Provides useful callbacks once descendant images have loaded.

waitForImages also supports both images referenced in CSS, such as the background-image property, and images referenced in element attributes such as srcset. Images referenced in attributes can also be a comma-separated list of images.

It can be useful when WebKit incorrectly reports element dimensions/offsets on document ready, because it has not calculated their descendant img dimensions yet.

Supports all browsers you probably care about.

##Get it##

You can either grab the source yourself...

• Production (minified)
• Development (unminified)

...or you can use a hosted version...

• Hosted on CDNJS (minified)

Alternatively, you can install with bower...

bower install waitForImages

...or npm...

npm install jquery.waitforimages

Of course, these need to be loaded after jQuery is made available. The current version should be supported by at least jQuery 1.8, or perhaps earlier. If you find incompatibility issues, please check out a previous tagged version.

##Usage##

There are two ways to use waitForImages: with a standard callback system (previously the only API) or receiving a promise.

###Standard###

Just provide a callback function and it will be called once all descendant images have loaded.

$('selector').waitForImages(function() {
    // All descendant images have loaded, now slide up.
    $(this).slideUp();
});

You can also use the jQuery promise API.

$('selector').waitForImages().done(function() {
    // All descendant images have loaded, now slide up.
    $(this).slideUp();
});

In the callbacks, this is a reference to the collection that waitForImages() was called on.

###Advanced###

You can pass a second function as a callback that will be called for each image that is loaded, with some information passed as arguments.

$('selector').waitForImages(function() {
    alert('All images have loaded.');
}, function(loaded, count, success) {
   alert(loaded + ' of ' + count + ' images has ' + (success ? 'loaded' : 'failed to load') +  '.');
   $(this).addClass('loaded');
});

Using the jQuery promises API, you can then use the progress() method to know when an individual image has been loaded.

$('selector').waitForImages().progress(function(loaded, count, success) {
   alert(loaded + ' of ' + count + ' images has ' + (success ? 'loaded' : 'failed to load') +  '.');
   $(this).addClass('loaded');
});

You can also set the third argument to true if you'd like the plugin to iterate over the collection and all descendent elements, checking for images referenced in the CSS (by default, it looks at the background-image, list-style-image, border-image, border-corner-image and cursor properties). If it finds any, they will be treated as a descendant image.

The callback will be called on the successful and unsuccessful loading of the image. Check the third argument to determine the success of the image load. It will be true if the image loaded successfully.

If you want to skip the first argument, pass $.noop or alternatively, pass an object literal to the plugin, instead of the arguments individually.

$('selector').waitForImages({
    finished: function() {
        // ...
    },
    each: function() {
       // ...
    },
    waitForAll: true
});

To use this with the promise API, simply pass one argument, which is waitForAll.

$('selector').waitForImages(true).done(function() {
    // ...
});

You may also set the CSS properties that possibly contain image references yourself. Just assign an array of properties to the plugin.

$.waitForImages.hasImgProperties = ['backgroundImage'];

waitForImages also exposes two custom selectors, img:has-src and img:uncached, (both used in conjunction with the img selector), which allow you to select img elements with a valid src attribute or that are not already cached already by the browser, respectively.

$('img').not(':has-src').remove();
$('img:uncached').attr('title', 'Loading Image');

##Feedback##

Please use the Issues for any bugs, feature requests, etc.

If you're having problems using the plugin, ask a question on Stack Overflow.