detect empty field - problem

I am trying detect in ajax what is the field that is emp开发者_如何学运维ty. (echo $field; >>> output is radios)

This if (!data.livre && data.livre == "radios") { checks if data.livre is not true (that is working) and now i want to check if the echo is radios or not. If is radios i showed to the user: empty radios

function check($form) {
            $fields = array("radios", "age");
            foreach($fields as $field) {
                if(empty($form[$field])) {
                    echo $field;
                    return false;
                }
            }
            return true;
    }

    $data = array();
    $data['livre'] = $val-> check($form);
    echo json_encode($data);

JSON output:

radios{"livre":false}

js

        success: function(data) {
             if (!data.livre && data.livre == "radios") { //problem here
                $("#msgbox1").fadeTo(200, 0.1, function() {
                 $(this).html('empty radios').addClass('messageboxerror1').fadeTo(900, 1);      
                });
            }
        }

EDIT: What is the best way to identify if the field that is empty is radios or age ?

thanks

---

If the result can be that only radios or age or none of both can be empty then you have to edit your check to !data.livres || data.livres == "radios" || data.livres == "age". It will then print the message if your json output is the following:

{livres: false}

or

{livres: "radios"}

or

{livres: "age"}

Edit: Changes according to your comment

if (!data.livre) { //problem here
  // Do whatever you want to do when livres is false
} else if (data.livre == "radios") {
  // Do whatever you want to do when livres is "radios"
} else if (data.livre == "age") {
  // Do whatever you want to do when livres is "age"
}