Validate a Textbox in ASP .NET without Validation Controls

Question

Validate a Textbox in ASP .NET to accept the below input without using validation controls

 

1. Accepting only numeric input

2. Accepting only characters.

3. Accepting alphanumeric input.

 

Note: Provide clear explanation with comments which is used for what purpose.

 

Task1: First use without using javascirpt

Task 2: With Javascript achieve the solution for the above