**Why Does an Infinite Loop Occur When Using useEffect in React?** **Answer and Explanation:** In React, the `useEffect` hook is designed to handle side effects such as data fetching, subscriptions, or DOM manipulations. An infinite loop often arises when the dependency array (dependency list) is improperly managed. **Common Causes:** 1. **Updating the state within `useEffect` while the state itself is included in the dependency array, and each update generates a new reference.** Example: ```jsx function MyComponent() { const [data, setData] = useState([]); useEffect(() => { setData([...data, 'new item']); // New array is created each time }, [data]); // `data` is the dependency } ``` Each call to `setData` triggers a re-render, creating a new `data` reference. The `useEffect` hook re-executes, leading to an infinite loop. 2. **Using objects or functions in the dependency array, which are re-created on each render.** Example: ```jsx useEffect(() => { fetchData(); }, [{ a: 1 }]); // New object is created each render ``` The `useEffect` hook is triggered repeatedly due to the re-creation of the dependency. **Solutions:** - **Use functional updates** to avoid relying on the state itself: ```jsx useEffect(() => { setData(prev => [...prev, 'new item']); }, []); // No dependency needed ``` - **For object/function dependencies**, use `useMemo`, `useCallback`, or move them outside the component (e.g., define them in a separate file or use `useRef` to retain stable references). - **Review the dependency array** to ensure only values that actually need to change are included. **Summary:** The root cause of an infinite loop in `useEffect` is when dependencies change after each render, triggering state updates that re-trigger the effect, creating a loop. Properly managing dependencies and state updates is critical to avoiding this issue.