It is the default way most tracking works: a JavaScript SDK fires events from the page. It is simple to set up and sees rich in-browser context, but it is also exposed to ad blockers and browser privacy limits like ITP, which is what server-side tracking exists to address.

In practice

Client-side is fine for most setups, but assume some data loss on privacy-restricted browsers and from ad blockers. When that loss becomes material, or you need events that never happen in a browser, move the critical paths server-side rather than trying to replace everything at once.