Issues with using Event Listeners in React Functional Components causing Memory Leaks
I'm experiencing memory leaks in my React application when I add event listeners to the window object inside a functional component. I am using React 17.0.2 and am trying to listen for scroll events to handle infinite scrolling. However, after navigating away from the component, the event listeners seem to persist, leading to performance issues. I've tried removing the listeners in a cleanup function, but it doesn't seem to work. Here’s how my component looks: ```javascript import React, { useEffect, useState } from 'react'; const InfiniteScroll = () => { const [items, setItems] = useState([]); useEffect(() => { const handleScroll = () => { const scrollHeight = document.documentElement.scrollHeight; const scrollTop = window.scrollY; const clientHeight = window.innerHeight; if (scrollTop + clientHeight >= scrollHeight - 5) { fetchMoreItems(); } }; window.addEventListener('scroll', handleScroll); return () => { window.removeEventListener('scroll', handleScroll); }; }, []); const fetchMoreItems = () => { // Simulated fetch function setItems(prevItems => [...prevItems, ...Array.from({ length: 10 }, (_, i) => i + prevItems.length)]); }; return ( <div> {items.map(item => <div key={item}>{item}</div>)} </div> ); }; export default InfiniteScroll; ``` In this code, I’m adding an event listener for scroll events when the component mounts and trying to remove it when the component unmounts. However, I notice that the scroll event handler still seems to be active even after navigating away from the page, which I verified using the Chrome Performance tab. I've also checked that there aren’t any lingering references to the component, and I'm not using any external libraries for state management that could be holding onto the component's state. Any insights on why this might be happening or how I can properly manage event listeners in functional components?