Your opinion: Best way to validate web forms
I've recently been handed the task to propose a standard to validate web forms in my companys systems.
I've been reading on the internet, and i came to this conclusion.
The best way to validate a web form would be:
-Validate in real time (when an input loses focus validate its content)
-Validate on submit (check all inputs before submitting)
-Validate on the server (validate that all data is correct on the server)
A person here at the office thinks that a "number" input should be made so that when the users is typing the input simply doesnt accept characters which are not in the [0-9] range (so that if you type an "A" for example, nothing appears on the input box).
I believe this is not a desirable thing, as it raises other problems such as.. what do to do with copy and paste functionality.
I'd like your opinion on this matter if it's not too much trouble.
Thanks in advance :D