Which answer is correct?

setTimeout has a minimum delay of 4ms in most browsers. Use `requestAnimationFrame` for zero-delay execution.

— browser_expert

Use `queueMicrotask(fn)` instead — microtasks run before the next macrotask, making them faster than setTimeout.

— microtask_fan

setTimeout(fn, 0) pushes the callback onto the macrotask queue. It runs after the current call stack clears and all pending microtasks (Promises) complete. This is by design — it defers work, not "runs immediately with no delay".

— event_loop_nerd

This is a browser bug. In Node.js, setTimeout(fn, 0) runs immediately.

— node_user