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Moodle 2.0

This document provides an overview of Moodle's use of YUI. The Yahoo! User Interface (YUI) framework is a fast, powerful, modular, and well-documented framework with a powerful loading system.

The Basics

YUI is an extremely extensible, fast, modular, and powerful JavaScript framework with a very capable loading system. A number of modules are available for YUI providing a wide range of functionality to suit most situations.

Since version 2.4, Moodle has included SimpleYUI rather than YUI, which includes several modules as standard including:

We recommend writing your code within a YUI module, but it is also possible to use one of the other methods to include your JavaScript. These include:

  • use within a javascript file included by a theme; and
  • inclusion of a module.js file.

Documentation and further information

Other YUI documentation you may find useful:

We will soon be adding API Documentation for Moodle-specific YUI modules in addition to the core YUI library.

Useful tools

JavaScript authoring have moved along considerably in recent years, and we highly recommend that you look at using some of the available tools to help you in your development. Most of these tools are available through <a href="http://nodejs.org">Node.js</a> which is relatively trivial to install on most operating systems:


<a href="http://jshint.com">JSHint</a> is a JSLint derivative for checking your code. This includes checking for errors and recommended stylistic approaches to writing JavaScript.

Since Moodle 2.5, a JSHint configuration is also included in the Moodle codebase to inform the tester of our preferences and recommendations.


Installation is relatively simple:

npm install jshint -g


Many IDEs and editors will automatically detect if you have JSHint installed and pass your code through it for you, reporting any errors as you go.

To run jshint on the command line, simply pass it the file that you wish to check:

jshint blocks/fruit/yui/fruitbowl/fruitbowl.js


There's a variety of documentation on JSHint and the error messages it returns. Start off with the jshint website:


<a href="http://yui.github.com/yuidoc/">YUIDoc</a> is a documentation system. It can work with any type of code, but is designed with JavaScript in mind. It's the documentation system used to create the YUI core API documentation, and will soon be used to create API documentation for Moodle-specific YUI modules in core.

We will soon start shipping a yuidoc.json configuration file if you'd like to generate your own documentation.


Installation is relatively simple:

npm install yuidoc -g


To run yuidoc across the entirety of Moodle JavaScript, from the root directory run:


Whilst writing your documentation, you may also like to run yuidoc in server mode. See the --server option for help on how to do this.


There's a variety of documentation on JSHint and the error messages it returns. Start off with the jshint website:


The upstream YUI project use a tool called <a href="http://yuilibrary.com/shifter">Shifter</a> to wrap up meta-data, rollup files, minify, and strip out debugging information from files. We will shortly be shifting to use of Shifter for core Moodle as it offers us many potential benefits.


Installation is relatively simple from the node.js Packaging Manager:

npm install shifter -g


There are two ways to run shifter depending on your intended use.

During development, we recommend you run shifter in --watch mode. To do so, enter the src directory of the module you are working on and run:

cd lib/yui/src
    shifter --watch

For more general use, you can run shifter across the whole of Moodle using --walk:

shifter --walk --recursive

See Also