Angularjs和服务器端返回值（PHP）

Question

Can someone explain to me why when my PHP script "returns" a value I get "undefined" in angularjs but when I print a value my response value is accurate.. What would my PHP have to do to return a json object?

This is my PHP

$postdata = file_get_contents("php://input");
$data = json_decode($postdata, true);

if ( $data['username'] == "myusername" && $data['password'] == "mypassword") {  
    $status = "success";
} else {
    $status = "failure";
}

print $status;

This is the part of my directive that deals with xhr request

    $http.post("http://lessons.localhost/login.php", user_data)
    .success(function(response) {

        switch (response) {

            case "success":
            sessionStorage.userStatus = "success";
            break;

            case "failure":
            sessionStorage.userStatus = "failure";
            break;

            default:
                sessionStorage.userStatus = "absent";
            break;
        }

      console.log(sessionStorage.userStatus);
      });

Answer 1

Can you try using echo json_encode(array('status'=>$status)); instead of print $status;

    $http.post("http://lessons.localhost/login.php", user_data, 
        function(response) {
         var result =  response.status;
            switch (result) {                        

                case "success":
                sessionStorage.userStatus = "success";
                break;

                case "failure":
                sessionStorage.userStatus = "failure";
                break;

                default:
                    sessionStorage.userStatus = "absent";
                break;
            }

          console.log(sessionStorage.userStatus);
          }, 'json');