When to use client-side or server-side? [closed]

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.

Answer 2

Javascript should be only used to manipulate the UI of the page. You can also do certain validations using it, however, there must be corresponding validation on the server-side. For doing any data manipulation, applying business logic, etc you should always use server side code.

Here are some cases where you will use client-side code:

• Changing the look (UI) of the page e.g. dynamically show/hide some elements
• Validate user inputs (this should also be done on server side)

Cases where to use server-side code:

• Validation of user inputs (should always be done on server side irrespective of whether done on client side or not.)
• User authentication
• Business logic (deciding what to show to which users, calculations)
• Database access