Frontend Performance60-90 min
React Memory Leak Debugging
Use cleanup functions, abort controllers, and browser heap tools to keep long-lived SPAs responsive.
ReactChrome DevToolsTypeScript
Prerequisites
- A React screen that slows down after repeated navigation or long usage.
- Chrome DevTools Memory panel.
- Knowledge of components that subscribe to external events.
1
Plan the implementation
Start by choosing the exact page, route, API, or deployment surface you want to improve. A narrow target makes the implementation measurable and easier to verify.
- Write down the current behavior and the user-facing problem it creates.
- Pick one measurable success signal such as bundle size, latency, error rate, security coverage, or UI responsiveness.
- Identify the files, routes, providers, and environment variables involved.
- Create a rollback note before changing production-sensitive configuration.
2
Set up the required tools
Install or configure only the tools needed for this implementation. Keep config close to the feature so future developers can find the moving parts quickly.
Implementation snippet
npm run dev
# Open Chrome DevTools > Memory > Heap snapshot.Checklist
- Dependencies are added to the correct workspace package.
- Environment variables are documented in `.env.example` when needed.
- Local development still starts without production-only secrets.
- The change is small enough to review in one pull request.
3
Implement the core pattern
- Reproduce the slowdown by navigating away and back several times.
- Record heap snapshots before and after repeated usage.
- Find components that create listeners, intervals, sockets, observers, or promises.
- Add cleanup functions and abort pending async work on unmount.
- Repeat the memory snapshot and confirm object counts stabilize.
Implementation snippet
useEffect(() => {
const controller = new AbortController();
const timer = window.setInterval(refreshData, 30_000);
window.addEventListener("resize", handleResize, { signal: controller.signal });
return () => {
controller.abort();
window.clearInterval(timer);
};
}, []);4
Handle edge cases
Checklist
- All `setInterval` and `setTimeout` calls are cleared.
- Event listeners and observers are removed on unmount.
- Fetch requests can be aborted when the component unmounts.
- WebSocket connections close when the related screen exits.
5
Verify before production
- Run the app locally and test the normal success path.
- Test one failure path, one empty state, and one slow-network or retry path.
- Run the project build and any related unit or integration tests.
- Check browser console, server logs, and network responses for hidden warnings.
- Document the final behavior, commands used, and any follow-up work.