When do I use Php or Javascript?

Question

I'm trying to create this dice betting game where you have a balance where you can use to get in the game and im just asking if when I should use php and javascript, like do I use php for all the system and javascript only for the animation ? or can js help in the system (sorry for the dumb question) :(

Answer 1

It used to be php for back-end and js for front-end.
But, today js can be used for both sides.

Answer 2

oh, can the onclick tag of a button contain a php function? (a php function that would manipulate the database(the balance of the user))

Answer 3

Maybe a js (frontend) that call php/js (backend) action?