How to return javascript variable to Ajax?

Question

Does anyone know how can I return the javascript variable to ajax instead of string value while I using ajax to call the php. Please see below example for more details:

Ajax:

 //Ajax Param 
 var paramList = "Action=make_process";

 ajaxRequest = $.ajax({
      url: "admin.php",
      type: 'POST',
      data: paramList,
      error: function(){
                  //error message here
      },
      success: function(data){
                 //read return javascript variable here;
      } 
     });

PHP:

public function validationChk()
    {
     $error_msg['error_msg'][] = array("msg"=>"hello");
            $error_msg['error_msg'][] = array("msg"=>"hi");

     echo "var ErrorMapping = " . json_encode($error_msg). ";\n\n";    
     exit;
    }

Answer 1

You wondering how you can return from an AJAX response?

Then check out this jQuery FAQ answer.

Answer 2

What you're trying to do isn't all that great of an idea. What you probably want is to decode the JSON response back into an object from within your success callback and then return that.

Decoding the JSON string involves piping it through eval and hoping you don't have bad/malicious data. The safe way to do this is to parse the JSON in Javascript. If you have to go this route on your own then at least try to use something already written. Search Google Code for "json-sans-eval".

The better option would be to use jQuery's built-in capabilities:

jQuery.getJSON( url, [data], [callback] )

It does all the hard stuff for you. Take some time to read through jQuery's docs. There's a lot of useful stuff there.