Cursor
ui
Event Listener Added Multiple Times
After Cursor refactored your component code, event listeners are being attached multiple times. Clicking a button fires the handler multiple times, or scroll events fire excessively.
The useEffect cleanup or listener removal logic was broken.
Error Messages You Might See
Handler called multiple times
Double-firing events
Excessive event firing
Memory leak from listeners
Common Causes
- useEffect missing dependency array, adding listener on every render
- Cleanup function not removing listener
- Multiple components mounting, each adding same global listener
- Event delegation not used, multiple listeners for same event
- Component mounting twice in strict mode (React 18)
How to Fix It
useEffect with cleanup: useEffect(() => { window.addEventListener(...); return () => window.removeEventListener(...); }, []). Empty dependency array ensures once per mount. Use event delegation for many items. In dev, React 18 mounts twice intentionally.
Real developers can help you.
Vlad Temian
15+ years shipping production infrastructure for startups. Former CTO at qed.builders (acquired by The Sandbox).
Cursor ambassador and agentic tooling builder.
I've scaled systems, automated deployments, and built observability tools for AI coding workflows. I specialize in taking vibe-coded apps from broken prototype to production-ready: fixing Supabase auth/RLS, Stripe integrations, deployment pipelines, and cleaning up AI-generated spaghetti.
I build tools in this space (agentprobe, claudebin, micode) and understand both sides: how AI generates code and why it breaks.
https://blog.vtemian.com/
Jen Jacobsen
I’m a Full-Stack Developer with over 10 years of experience building modern web and mobile applications. I enjoy working across the full product lifecycle — turning ideas into real, well-built products that are intuitive for users and scalable for businesses.
I particularly enjoy building mobile apps, modern web platforms, and solving complex technical problems in a way that keeps systems clean, reliable, and easy to maintain.
Victor Denisov
Developer
Matthew Butler
Systems Development Engineer @ Amazon Web Services
AUXLE
I am a Full Stack Developer experienced in building Websites, Web apps and Cross Platform Mobile Apps for Startups and Companies.
hanson1014
Full-stack developer experienced in fixing and deploying AI-generated apps from Lovable, Bolt.new, Cursor, and Replit. I specialize in debugging Supabase integration issues (auth flows, RLS policies, database connections), fixing broken deployments, resolving routing/blank screen problems, and cleaning up messy React/Vite codebases. I also build production apps with the Claude API and have shipped a Mac desktop dev tool (Nexterm from scratch. Based in Hong Kong, fast turnaround.
Costea Adrian
Embedded Engineer specilizing in perception systems. Latest project was a adas camera calibration system.
Prakash Prajapati
I’m a Senior Python Developer specializing in building secure, scalable, and highly available systems. I work primarily with Python, Django, FastAPI, Docker, PostgreSQL, and modern AI tooling such as PydanticAI, focusing on clean architecture, strong design principles, and reliable DevOps practices. I enjoy solving complex engineering problems and designing systems that are maintainable, resilient, and built to scale.
Richard McSorley
Full-Stack Software Engineer with 8+ years building high-performance applications for enterprise clients. Shipped production systems at Walmart (4,000+ stores), Cigna (20M+ users), and Arkansas Blue Cross. 5 patents in retail/supply chain tech. Currently focused on AI integrations, automation tools, and TypeScript-first architectures.
Matt Butler
Software Engineer @ AWS
You don't need to be technical. Just describe what's wrong and a verified developer will handle the rest.
Get HelpFrequently Asked Questions
Why is my listener firing twice?
Missing cleanup function in useEffect. Or missing dependency array, adding listener on every render.
What's event delegation?
Add one listener to parent, check event.target. Better than adding listener to every child. Reduces memory.