Difference between JavaScript Functions and CSharp Functions in Update Panel of ASP.Net AJAX

Hi

I want to use a Web Service in My Asp.Net AJAX Page.

I created a Proxy Reference to the Web Service.

Now I want to use the Web Methods that are present in the Web Service.

I want to know the difference between Writing the methods in Java Script and Csharp File.

For Example :

Scenario 1 :

I have a asp text box and asp button in my update panel.

If i Double click on the asp button. It will open aspx.cs file and I can write the code in aspx.cs file. I can create the object of my webservice and use it.

Scenario 2 :

I have a HTML textbox and a HTML button in Update Panel. If I double click on the HTML button it will open the source view and I can write the JavaScript code in Source view itself.

 

Now Which one is the best way. I can write easily in Codebehind (.aspx.cs) when compared to Javascript in the Source View. Please suggest me.

P ...