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.
Matthew Jordan
I've been working at a large software company named Kainos for 2 years, and mainly specialise in Platform Engineering. I regularly enjoy working on software products outside of work, and I'm a huge fan of game development using Unity. I personally enjoy Python & C# in my spare time, but I also specialise in multiple different platform-related technologies from my day job.
Alvin Voo
I’ve watched the tech landscape evolve over the last decade—from the structured days of Java Server Pages to the current "wild west" of Agentic-driven development. While AI can "vibe" a frontend into existence, I specialize in the architecture that keeps it from collapsing.
My expertise lies in the critical backend infrastructure: the parts that must be fast, secure, and scalable. I thrive on high-pressure environments, such as when I had only three weeks to architect and launch an Ethereum redemption system with minimal prior crypto knowledge, turning it into a major revenue stream.
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Forensic Debugging: I don't just "patch" bugs; I use tools like Datadog and Explain Analyzers to map out bottlenecks and resolve root causes—like significantly reducing memory usage by optimizing complex DB joins.
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Sanity in the Age of AI: I bridge the gap between "best practices" and modern speed, ensuring your project isn't just built fast, but built to last.
Matt Butler
Software Engineer @ AWS
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/
rayush33
JavaScript (React.js, React Native, Node.js) Developer with demonstrated industry experience of 4+ years, actively looking for opportunities to hone my skills as well as help small-scale business owners with solutions to technical problems
Anthony Akpan
Developer with 8 years of experience building softwares fro startups
Caio Rodrigues
I'm a full-stack developer focused on building practical and scalable web applications. My main experience is with **React, TypeScript, and modern frontend architectures**, where I prioritize clean code, component reusability, and maintainable project structures.
I have strong experience working with **dynamic forms, state management (Redux / React Hook Form), and complex data-driven interfaces**. I enjoy solving real-world problems by turning ideas into reliable software that companies can actually use in their daily operations.
Beyond coding, I care about **software quality and architecture**, following best practices for componentization, code organization, and performance optimization.
I'm also comfortable working across the stack when needed, integrating APIs, handling business logic, and helping transform prototypes into production-ready systems.
My goal is always to deliver solutions that are **simple, efficient, and genuinely useful for the people using them.**
Simon A.
I'm a backend developer building APIs, emulators, and interactive game systems. Professionally, I've developed Java/Spring reporting solutions, managed relational and NoSQL databases, and implemented CI/CD workflows.
MFox
Full-stack professional senior engineer (15+years). Extensive experience in software development, qa, and IP networking.
Daniel Vázquez
Software Engineer with over 10 years of experience on Startups, Government, big tech industry & consulting.
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.