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https://github.com/lukasbombach/lazyloader

A tiny JavaScript/CSS lazyloader that also calls callbacks for CSS-Files!
https://github.com/lukasbombach/lazyloader

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A tiny JavaScript/CSS lazyloader that also calls callbacks for CSS-Files!

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Luke's Lazyloader
=========

#### A tiny lazyloader for JavaScript and CSS that also calls onload-callbacks for CSS files ####

There are tons of lazyloaders out there and frameworks like Mootools or YUI have built-in funtionality for this. But they all fail to reliably detect or call a callback when CSS files have been loaded and applied. This is simply because link-tags (contrary to script-tags) don't always have a onload-property that calls a function when, well, the file has been loaded.

### Different browsers, different implementations ###

It's funnny. All major browsers implement an onload-propery on script-tags. Link-tags only have that property in Opera. Internet Explorer 6-8 have onreadystatechange-callbacks like XHR-calls and Firefox and Safari provide no such funtionality whatsoever.

### What can we do? ###

Behnam Taraghi (http://tugll.tugraz.at/96784/) had a clever idea to fix the Firefox/Safari issues. It's fairly simple: Create link-tags and poll them until they have a .cssRules-property. Unfortunately his code (http://tugll.tugraz.at/96784/weblog/9080.html) was kind of buggy and *only* supported FF/Safari. So, along with a private project I'm working on I created this lazyloader that works with CSS- and JavaScript-Files and supports every major browser.

Features
--------

* [x] Lazyload JavaScript & CSS
* [x] Pass multiple files to the loader
* [x] Pass a callback that will be called when all files have been loaded
* [x] Use Bower, AMD or CommonJs
* [x] Tiny code, no dependencies

Installation
------------

```shell
bower install lukeslazyloader
```

Or [download `lazyloader.js` from GitHub](https://raw.githubusercontent.com/LukasBombach/Lazyloader/master/lazyloader.js).

Use a script node, AMD or CommonJs (with Webpack, Browserify, …)

```html

```
```javascript
require(["bower_components/lukeslazyloader/lazyloader"], function(LukesLazyLoader) { });
```
```javascript
var LukesLazyLoader = require("bower_components/lukeslazyloader/lazyloader");
```

Usage
-----

```javascript
LukesLazyLoader.load('your', 'css', 'and', 'js', 'files').then(callback).then(anotherCallback);
```
whenever you need it. If you need seperate callbacks for each file simply call

```javascript
LukesLazyLoader.load('file1').then(callback1);
LukesLazyLoader.load('file2').then(callback2);
LukesLazyLoader.load('file3' 'file4').then(callback3);
```

Compatibility
-------------

I've tested this with

* Safari 5
* Firefox 3.6
* Opera 10.10
* Internet Explorer 6, 7, 8

Todo
----

* [ ] Improve API
* [ ] Chainability to successively load files
* [ ] Integration with [q](https://github.com/kriskowal/q)
* [ ] Minification
* [ ] Tests
* [ ] Improve Demo

License
-------

MIT