Chrome为PHP AJAX响应添加了其他字符

Question

Chrome shows additional chars at the beginning and ending of the response because of that I cant use if statements such as

if(result=="Saved"){
   alert("Yihuu");
}  

With firefox I dont have any problems.

How can I prevent this issue?

JavaScript Code

$.ajax({
            url: "http://localhost:8080/RestHmdy/api.php/register",
            type: "POST",
            data: JSON.stringify(user),
            contentType: 'application/json; charset=utf-8',

            success: function (result) {

               alert(result);

            },

            error: function (xhr, status, err) {

                 alert("Error "+err,xhr,status);

             }

     })

PHP Response Code

if($stmt->execute()){

                    echo "Saved";

                }else{

                    echo "Unsaved";                 
                }

Firefoxs Pure Alert

Chrome Broken Alert