The jQuery library and virtually all of its plugins are contained within the jQuery namespace. As a general rule, global objects are stored inside the jQuery namespace as well, so you shouldn't get a clash between jQuery and any other library (like prototype.js, MooTools, or YUI).
That said, there is one caveat: by default, jQuery uses $ as a shortcut for jQuery. Thus, if you are using another JavaScript library that uses the $ variable, you can run into conflicts with jQuery. In order to avoid these conflicts, you need to put jQuery in no-conflict mode immediately after it is loaded onto the page and before you attempt to use jQuery in your page.
Putting jQuery Into No-Conflict Mode
When you put jQuery into no-conflict mode, you have the option of assigning a new variable name to replace the $ alias.
<!-- Putting jQuery into no-conflict mode. -->
<script src="prototype.js"></script>
<script src="jquery.js"></script>
<script>
var $j = jQuery.noConflict();
// $j is now an alias to the jQuery function; creating the new alias is optional.
$j(document).ready(function() {
$j( "div" ).hide();
});
// The $ variable now has the prototype meaning, which is a shortcut for
// document.getElementById(). mainDiv below is a DOM element, not a jQuery object.
window.onload = function() {
var mainDiv = $( "main" );
}
</script>
In the code above, the $ will revert back to its meaning in original library. You'll still be able to use the full function name jQuery as well as the new alias $j in the rest of your application. The new alias can be named anything you'd like: jq, $J, awesomeQuery, etc.
