Question

Is there any way to check in sfContext whether jQuery library is already added,
using:

sfContext::getInstance()->getResponse()->addJavascript('/js/jquery-1.4.2.min.js');

or

addJavascript('jquery-1.4.2.min.js', sfView::getContext());

or

use_javascript('jquery-1.4.2.min.js');

in the templates?

Seems to me that adding more jQuery’s stops their action.

Answer 1

You should use your own check.

1. Use your own sfWebResponse
2. Override addJavascript
3. Add the check

So create a new myWebResponse.class.php file in /lib/response/ folder (create it), with this code :

class myWebResponse extends sfWebResponse 
{
  public function addJavascript($file, $position = '', $options = array())
  {
    $this->validatePosition($position);

    // check if the file to add is jquery
    // nb: you might update the regex 
    if (preg_match('/jquery/i', $file))
    {
      // retrieve all loaded js
      $files = array_keys($this->getJavascripts());

      // check if one them containt jquery
      // nb: you might update the regex 
      $isJquery = preg_grep("/jquery/i", $files);

      // jquery found so do not add the file
      if ( ! empty($isJquery))
      {
        return;
      }
    }

    $this->javascripts[$position][$file] = $options;
  }

Then, use your new response by default. In your apps/frontend/config/factories.yml, add:

all:
  response:
    class: myWebResponse 

You’re done.