jQuery & Greasemonkey

How to play nicely with jQuery and Greasemonkey

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Overview

This is a simple snippet that helps us load the jQuery power into our userscripts with Greasemonkey 0.7 or lower, newer versions may use @require .

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Updates

2010-04-24:
The userscript checks if jQuery is already loaded in the page and uses it, otherwise loads it from Google's CDN. It's also using jQuery.noConflict(true).

Thanks to everyone who sent me emails about this over this and last year.

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Code

javascript:

var $;

// Add jQuery
(function(){
if (typeof unsafeWindow.jQuery == 'undefined') {
var GM_Head = document.getElementsByTagName('head')[0] || document.documentElement,
GM_JQ = document.createElement('script');

GM_JQ.src = 'http://ajax.googleapis.com/ajax/libs/jquery/1/jquery.min.js';
GM_JQ.type = 'text/javascript';
GM_JQ.async = true;

GM_Head.insertBefore(GM_JQ, GM_Head.firstChild);
}
GM_wait();
})();

// Check if jQuery's loaded
function GM_wait() {
if (typeof unsafeWindow.jQuery == 'undefined') {
window.setTimeout(GM_wait, 100);
} else {
$ = unsafeWindow.jQuery.noConflict(true);
letsJQuery();
}
}

// All your GM code must be inside this function
function letsJQuery() {
alert($); // check if the dollar (jquery) function works
alert($().jquery); // check jQuery version
}