Question

I just finished an intro to web dev course in my CS program and came away wondering something simple. When should you use JavaScript (client-side) instead of server-side (we used PHP but anything applies) code? Vice-versa as well.

Answer 1

There is no recipe for deciding that. A few notes:

• security and validation should always be present at the server side (sometimes duplicated in the client).
• the client-side should contain only UI-logic. No business logic.
• logically, everything that accesses a database should be on the server.

Of course, if your application is a RIA (rich internet app), then you can have logic on the client. So it all depends.