Recently I have started working with Drupal 7. Drupal is a CMS built on top of PHP, MySQL, and jQuery. In Drupal, a website layout is managed by a Theme. Boostrap Themes can be plugged in – or, you can roll your own. At Qualcomm, my group created a custom theme that required a newer version of JQuery (1.11) than Drupal 7 provided (1.4).

Initially, our custom theme loaded the newer version of jQuery. Drupal 7 allows this as it uses jQuery’s .noConflict() function. .noConflict() is frees up jQuery’s $ alias for other frameworks to use. In this case the “other” framework … was just a newer version of jQuery.

There were two problems with this …

1. We were loading jQuery TWICE. When visiting the site Drupal would load jQuery 1.4 – and then our custom theme would load jQuery 1.11.
2. We discovered that any jQuery plugins loaded by Drupal for jQuery 1.4 needed to be reloaded by our custom theme after it loaded jQuery 1.11.

I found this out the hard way. I kept getting TypeError: $(…).once is not a function” errors. This was because our custom theme required the jquery.once.js plugin. This plugin was initially loaded by Drupal when it loaded JQuery 1.4 – but subsequentally wiped out by our custom theme’s newer JQuery.

To fix this we did the following …

1. We added the desired version of JQuery to our custom theme :

   \sites\all\themes\[custom_theme]\js\jquery-x.x.x.js

2. We added this statement to our custom themes template.php :

   So, in this file :

   \sites\all\themes\[custom_theme]\template.php

   We added this code :

   		function [custom_theme]_js_alter(&$javascript) {
   			$javascript['misc/jquery.js']['data'] = drupal_get_path('theme', '[custom_theme]') . '/js/jquery-x.x.x.js';
   		}
   		

   This will instruct Drupal to swap out the version of jQuery (1.4) it uses with the version that resides in your custom theme. :

3. We encapsulated any javascript used by our custom theme into a Javascript module and injected jQuery into it.

   For example :

   Behavior = (function($){
   
   	$( document ).ready(function() {
   
   	});
   
   	// Public Interface.
   	return {
   
   		myFunc : function () {
   
   		}
   	}
   }(jQuery));
   

   Notice that jQuery is injected rather than its $ alias. As I mentioned earlier this is because Drupal invokes jQuery’s .noConflict() function. To tidy things up a bit I inject jQuery as $.

4. We stopped our custom theme from loading its own version of jQuery. It is no longer necessary as (1) and (2) above will force Drupal to use whatever version of jQuery you desire.

   So in this file :

   sites/all/themes/[custom_theme]/[custom_theme].info

   We removed this :

   			scripts[] = 'js/jquery-x.x.x.js' <=== comment this out.
   			

I Hope this helps! Let me know if you have any questions!

-Scott

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