🧹 Why Cleanup Functions Matter in useEffect

When using useEffect, sometimes you need to clean up resources like timers, subscriptions, or event listeners.

📘 Example:

import { useEffect } from "react";

function Timer() {
  useEffect(() => {
    const timer = setInterval(() => {
      console.log("Running...");
    }, 1000);

    return () => clearInterval(timer); // cleanup
  }, []);
}

✨ Key Points:
• Cleanup prevents memory leaks
• Runs when the component unmounts
• Also runs before the effect executes again

Always clean up side effects to keep your React apps efficient and bug-free. 🚀