#ajax response handler function Hi I am using #ajax in my custom form. I need a response handler function for my form in jquery. How can i acheive this goal? 

For example: 

$form['changethis'] = array(
'#type' =&gt; 'select',
'#options' =&gt; array(
  'one' =&gt; 'one',
  'two' =&gt; 'two',
  'three' =&gt; 'three',
),
'#ajax' =&gt; array(
  'callback' =&gt; 'ajax_example_simplest_callback',
  'wrapper' =&gt; 'replace_textfield_div',
 ),
);


Here i have the ajax_example_simplest_callback in php. I need a response handler in js.
Try this

(function($) {

  Drupal.YOUR_MODULE_NAME = {
    form_id: 'FORM_ID'  
  };

  Drupal.behaviors.YOUR_MODULE_NAME = {
   attach: function(context, settings) {

    for (ajax_el in settings.ajax) {
      if (Drupal.ajax[ajax_el].element.form) {
        if (Drupal.ajax[ajax_el].element.form.id === Drupal.YOUR_MODULE_NAME.form_id) {
          Drupal.ajax[ajax_el].success = Drupal.YOUR_MODULE_NAME.success;
       }
      }
     }
    }   
   };


 Drupal.YOUR_MODULE_NAME.success = function (response, status) {
    // HERE YOU GET THE response
 }

 });