Sep 30 2012
Sep 30

I recently worked on a project which required a updated version of the jQuery library. While there is the jQuery Update module, it only allows you to upgrade Drupal 6 to jQuery 1.3. If you really know what you're doing and want to upgrade beyond that version, you can either hack core or create your own simple module to do it. While hacking core is certainly the easier approach (simply overwriting misc/jquery.js with a newer version), it is very bad practice. You do not want to get yourself in the habit of altering Drupal core unless you want to kill your upgrade path and deal with a new slew of bugs and unpredictable behavior.

Let's start by creating an admin area for configuring the version of jQuery we want to use.

<?php
/**
* Module configuration admin form.
*
*/
function mymodule_admin_form() {
 
$form['mymodule_custom_jquery'] = array(
   
'#type' => 'checkbox',
   
'#title' => t('Override Jquery'),
   
'#description' => t('Replace the version of jQuery that ships with Drupal
      (jQuery 1.2.6) with the jQuery library specified below. You will need to
      flush your cache when turning this feature on or off.'
),
   
'#default_value' => variable_get('mymodule_custom_jquery', 0),
  );
 
$form['mymodule_custom_jquery_file'] = array(
   
'#type' => 'textfield',
   
'#title' => t('Jquery file location'),
   
'#description' => t('Specify the location of the updated jQuery library
      you would like to use. The location is relative to the docroot and
      so should probably begin with "sites/".'
),
   
'#size' => 128,
   
'#default_value' => variable_get('mymodule_custom_jquery_file', NULL),
  );
$form = system_settings_form($form);

  return

$form;
}
?>

Next, we're going to write a validation hook that simply makes sure the file exists.

<?php
/**
* Admin form validation callback.
*
*/
function mymodule_admin_form_validate($form, &$form_state) {
 
$file = trim($form_state['values']['mymodule_custom_jquery_file']);
 
$form_state['values']['mymodule_custom_jquery_file'] = $file; // Only validate this value if js override is turned on
 
if (variable_get('mymodule_custom_jquery', 0)) {
    if (!
file_exists($file)) {
     
form_set_error('mymodule_custom_jquery_file', t('The file you specified does not exist: !file.', array('!file' => $file)));
    }
  }
}
?>

And lastly, we use hook_preprocess_page() to safely replace the jQuery that ships with Drupal core with our own version.

<?php
/**
* Implementation of hook_preprocess_page().
*/
function mymodule_preprocess_page(&$variables) {
  if (
variable_get('mymodule_custom_jquery', 0)) {
   
$file = variable_get('mymodule_custom_jquery_file', 0);
   
$scripts = drupal_add_js(); // remove core jquery and add our own
   
unset($scripts['core']['misc/jquery.js']);
   
$add_scripts['core'][$file] = array(
     
'cache' => TRUE,
     
'defer' => FALSE,
     
'preprocess' => TRUE,
    );
   
$scripts['core'] = array_merge($add_scripts['core'], $scripts['core']);
   
$variables['scripts'] = drupal_get_js('header', $scripts);
  }
}
?>

Make note of the line:

<?php
    $scripts
['core'] = array_merge($add_scripts['core'], $scripts['core']);
?>

We are careful to add our new jQuery include at the beginning of the array (where the original jquery.js include was) in order to meet any jquery dependencies in the scripts that follow.

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