ResourceLoader

ResourceLoader is a JavaScript/CSS delivery system for MediaWiki, available in version 1.17 and later. Code that has not been explicitly integrated into ResourceLoader should still function, with some caveats; migration is highly recommended.

Documentation
Documentation is still a work in progress, but there's already enough to get most developers started.
 * Getting extensions to work ResourceLoader
 * Getting a development environment configured properly

Additional documentation on various topics is also available.
 * Status of the project
 * Design specifications developed and maintained throughout the development process
 * Deprecated JavaScript features planed to be replaced with modern equivalents
 * Requirements gathered from a variety of sources during the planning stage

About ResourceLoader
On Wikimedia wikis, every page view includes hundreds of kilobytes of JavaScript. In many cases some or all of this code goes unused due to browser support or because users do not make use of the features on the page. In these cases, bandwidth and loading time spent on downloading, parsing and executing JavaScript code is being wasted. This is especially true when users visit MediaWiki sites using older browsers like Internet Explorer 6, where almost all features are unsupported, and parsing and executing JavaScript is extremely slow.

ResourceLoader solves this problem by allowing resources to only be loaded on browsers can run them and allowing resources to be loaded on demand. It also improves client-side performance by reducing the size of resources by minifying JavaScript and CSS code and reducing the number of requests by batch loading resources and optionally embedding images as data URIs.

Todo

 * Test plan (in a Google document somewhere)
 * Documentation plan
 * Schedule (in a Google document somewhere)
 * Task management (Mostly in Google Docs. There is a tracking bug in Bugzilla)
 * Release management plan
 * Community management plan