What is the Web Animations API (WAAPI), and when should I use it?

WAAPI is the browser-native middle ground: it gives you JavaScript-level control (play, pause, reverse, finish callbacks) while still running on the compositor for transform and opacity. It's great for simple programmatic animations without pulling in a library. It's not yet a full replacement for GSAP, though — it lacks timeline orchestration, ScrollTrigger integration, and the plugin ecosystem that complex production work relies on.