What are the dependencies in React's useEffect hook?

Can you explain what dependencies are in the useEffect hook in React?

Sure! In React, the useEffect hook allows you to perform side effects in function components. Dependencies are values that the effect depends on; if they change, the effect runs again.

How do I specify dependencies in useEffect?

You specify dependencies by passing an array as the second argument to useEffect. For example: useEffect(() => { /* effect */ }, [dependency1, dependency2]);

What happens if I leave the dependency array empty?

If you leave the dependency array empty, the effect runs only once after the initial render, similar to componentDidMount.

Can I use state variables as dependencies?

Yes, you can use state variables as dependencies. The effect will re-run whenever those state variables change.