What is the purpose of the dependency array in useEffect?

What is the purpose of the dependency array in useEffect?

The dependency array in useEffect determines when the effect runs. If values in the array change, the effect re-runs.

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

Sure! If you want to fetch data when a component mounts or when a specific prop changes, you can do this:

useEffect(() => {
  fetchData();
}, [prop]);

What happens if I leave the dependency array empty?

If you leave it empty, the effect runs only once when the component mounts, similar to componentDidMount.

Is it possible to have multiple dependencies?

Yes, you can include multiple dependencies in the array. The effect will re-run if any of those values change.