What is the useEffect hook in React?

What is the useEffect hook in React?

The useEffect hook is a built-in React hook that allows you to perform side effects in function components.

Can you give me an example of how to use it?

Sure! You can use useEffect to fetch data when a component mounts. Here's a simple example:

useEffect(() => {
  fetch('https://api.example.com/data')
    .then(response => response.json())
    .then(data => setData(data));
}, []);

What does the empty array mean in that example?

The empty array means that the effect runs only once, similar to componentDidMount in class components.

Can useEffect be used for cleanup?

Yes! You can return a cleanup function from useEffect to clean up resources when the component unmounts or before the effect runs again.