Cleanup Functions in useEffect: Stop Leaks Before They Start

Short summary

This tutorial explains how to write correct cleanup functions in React's useEffect hook to prevent memory leaks, duplicate handlers, and setState errors on unmounted components. It covers essential scenarios including DOM events, intervals, subscriptions, and fetch requests with AbortController. The article includes concrete code examples and a pre-merge checklist for ensuring every resource has a proper teardown path.

• •Explains useEffect cleanup with code examples for events, timers, subscriptions, and fetch
• •Covers Strict Mode behavior and common mistakes like stale closures and missing aborts
• •Includes a practical pre-merge checklist for verifying cleanup correctness

Generated with AI, which can make mistakes.