I use JQuery to get Json data, but the data it display has double quotes. It there a function to remove it?
$(\'div#ListingData\').text(JSON.stringify(data.         
        Use replace:
var test = "\"House\"";
console.log(test);
console.log(test.replace(/\"/g, ""));  
// "House"
// House
Note the g on the end means "global" (replace all).
I dont think there is a need to replace any quotes, this is a perfectly formed JSON string, you just need to convert JSON string into object.This article perfectly explains the situation : Link
Example :
success: function (data) {
        // assuming that everything is correct and there is no exception being thrown
        // output string {"d":"{"username":"hi","email":"hi@gmail.com","password":"123"}"}
        // now we need to remove the double quotes (as it will create problem and 
        // if double quotes aren't removed then this JSON string is useless)
        // The output string : {"d":"{"username":"hi","email":"hi@gmail.com","password":"123"}"}
        // The required string : {"d":{username:"hi",email:"hi@gmail.com",password:"123"}"}
        // For security reasons the d is added (indicating the return "data")
        // so actually we need to convert data.d into series of objects
        // Inbuilt function "JSON.Parse" will return streams of objects
        // JSON String : "{"username":"hi","email":"hi@gmail.com","password":"123"}"
        console.log(data);                     // output  : Object {d="{"username":"hi","email":"hi@gmail.com","password":"123"}"}
        console.log(data.d);                   // output : {"username":"hi","email":"hi@gmail.com","password":"123"} (accessing what's stored in "d")
        console.log(data.d[0]);                // output : {  (just accessing the first element of array of "strings")
        var content = JSON.parse(data.d);      // output : Object {username:"hi",email:"hi@gmail.com",password:"123"}" (correct)
        console.log(content.username);         // output : hi 
        var _name = content.username;
        alert(_name);                         // hi
}