WordPress: Allow Using Ajax Request on Theme

Sometimes we need to have ajax in wordpress element in order to retrieve sub-categories, or anything. To allow using ajax, this several steps can make it happen.

1. Add below code under the functions.php file inside theme folder.
   [code lang=”php”]
   function implement_ajax() {
   if(isset($_POST[‘main_catid’]))
   {
   $categories= get_categories(‘child_of=’.$_POST[‘main_catid’].’&hide_empty=0′);
   foreach ($categories as $cat) {
   $option .= ‘<option value="’.$cat->term_id.’">’;
   $option .= $cat->cat_name;
   $option .= ‘</option>’;
   }
   echo ‘<option value="" selected="selected">Select Model</option>’.$option;
   die();
   } // end if
   }
   add_action(‘wp_ajax_my_special_action’, ‘implement_ajax’);
   add_action(‘wp_ajax_nopriv_my_special_action’, ‘implement_ajax’);//for users that are not logged in.
   [/code]
   main_catid is the query pass from javascript
2. On the front end, just create default ajax javascript that has query man_catid and action that assigned to my_special_action that is from add_action('wp_ajax_[<action name>]', 'implement_ajax');