Question

I basically have an ajax function which gets the latest posts from a database, what I want to know is if no data is found what should I return seeing as returning null seems to be an issue for firebug?

php code

function getLatestChat(){
   global $session, $form;

   $data = $session->getLatestChat(mysql_real_escape_string($_REQUEST['withUser']),
      mysql_real_escape_string($_REQUEST['ignoreMessages']));

   if($data){//successful
      echo json_encode($data);   
   }        

   return;
}

jquery code

function getLatestChat(){
   var ignoreMessagesArr = $(".chatID").map(function(){ return this.value;}).get().join(",");

   $.ajax({
      traditional: true,
      dataType: "json",
      type: "GET", url: "include/process.php", 
      data:{
      getLatestChat: "true",
         withUser: currentCCID,
     ignoreMessages: ignoreMessagesArr
      },
      success: function(data){
         $.each(data, function(i, elem){
        $('.chat-latestContainer').append(elem.value);
     });             
      }
   }
});   

at the moment the method either returns the $data object or null.

Answer 1

You can return an empty object to represent no data in the object:

return '{}';

Or if your Javascript code expects an array, return an empty array:

return '[]';