React 19.2 useEffectEvent: Kill Stale Closures in Effects

If you have ever stared at a React Effect that logs the wrong value or tears down a perfectly good websocket every time the user toggles dark mode, you have met the stale closure. useEffectEvent — stable in React 19.2 — is the official fix. It lets you read the latest props and state from inside an Effect without making them dependencies.

This guide walks through the problem, the workarounds people have been using for years (refs, ESLint disables, manual sync), and how useEffectEvent replaces all of them. By the end you will know exactly when to reach for it, when not to, and how to refactor an Effect that is fighting you today.