How to disable/enable keys

You can use regex and disable input for those characters you don't allow.

Here is example Code

In regex string you can put or remove characters you don't want to allow like in here, allowed characters are:
- letters from a-z (lowercase)
- letters from A-Z (uppercase)
- numbers from 0-9
- space
- dot
- @ sign
- #sign
- $ sign
- % sign
- & sign

PHP Code:

[a-zA-Z0-9 .@#$%&] 


Thanks @brianjamestorr but is that Javascript, PHP or other?

Can you give an example of some coding?