Which processing is fast Client-side or Server-side? for client side processing browser need to download every JavaScript first and in server side programming everything happens on server without downloading anything to user PC?
if for a particular functionality we have solution in both javascript and php/asp then what should be chosen and why?
Downloading the JavaScript upfront is usually quicker as a server round trip isn’t required (and it is networking operations that are usually the most time consuming).
That said, there should always be a server side solution for any essential functionality (as JS support is not guaranteed), and performance shouldn’t be the first thing you think about (trust should be, e.g. you can’t trust client side code to make certain that data isn’t going to trash your database).