Third-Party Libraries

With the @require metadata imperative, one can include entire extra files into a user script. This can also be used for including entire third-party libraries like jQuery or YUI.

Most general purpose libraries are not written to operate within the Greasemonkey sandbox and thus may not work properly, so tread carefully.

jQuery

For a simple example, here is a way to load and use jQuery in your user scripts. Note that @require works by downloading the files once, at install time, and is thus fast and efficient.

// ==UserScript==
// @name          jQuery Example
// @require       http://ajax.googleapis.com/ajax/libs/jquery/1.4.2/jquery.min.js
// ==/UserScript==

// Append some text to the element with id #someText using the jQuery library.
$("#someText").append(" more text.");

YUI

Sometimes using the @resource imperative alongside @require can be helpful.

YUI has a nice tool to bundle your required libraries on the fly. After you receive your script source (Loading Script and CSS Directly box) use the @require key for the script and @resource for the CSS (if any).

For example:

// ==UserScript==
// @name           YUI Example
// @require        http://yui.yahooapis.com/combo?2.8.0r4/build/yahoo-dom-event/yahoo-dom-event.js&2.8.0r4/build/element/element-min.js&2.8.0r4/build/datasource/datasource-min.js&2.8.0r4/build/datatable/datatable-min.js
// @resource       yCSS http://yui.yahooapis.com/combo?2.8.0r4/build/datatable/assets/skins/sam/datatable.css
// ==/UserScript==

// add Yahoo! css to head
var yCSS = GM_getResourceText("yCSS");
GM_addStyle(yCSS);

Without @require

For older versions of Greasemonkey (before 0.8) or for other user script managers, there is an alternative approach. This, however, does not have the download-once-at-install-time benefit, so you should not reference servers that you do not own (i.e. jquery.com or yahoo.com). Read about this technique at jQuery & Greasemonkey.