Not sure should I use Ajax or ASP back code since I need an object to do append loop at front end

Not sure what you are trying to do but I think you need to do some research.

Asp is the code that runs on the server (backend). There are alternatives such as php and node.js

Ajax is the process of sending data between the client and server (front end and backend) without having to reload the page each time.

You can use ajax and asp together.

AJAX = Async JavaScript and XML
ASP = Some MS web server platform