Custom Controls (. ascx)

I read a blog by Lao Zhao about user-defined controls and have a better understanding of user-defined controls.
Http://blog.zhaojie.me/2007/12/usercontrol-as-an-template.html

Including:
1. Custom Controls.
2. Prototype Ajax framework.
3. General handlingProgram.
Objective: To use the HTML generated by usercontrol to request a general Handler through Ajax (prototype), and output HTML to a custom location.
Advantage: the use of user-defined controls is better than self-writing classes, and then concatenate strings.
...

Source code: refresh the entire page
Complete partial Ajax refresh