useDebugValue hook in react

useDebugValue is a hook that allows you to display custom debugging information for custom hooks in the React DevTools. This can be useful for debugging hooks and understanding what's happening behind the scenes.

Here’s an example of how to use useDebugValue:

import { useState, useEffect, useDebugValue } from 'react';

function useFetch(url) {
  const [data, setData] = useState(null);

  useEffect(() => {
    fetch(url)
      .then(response => response.json())
      .then(data => setData(data));
  }, [url]);

  useDebugValue(data ? `Data loaded: ${data.length} items` : 'Loading...');

  return data;
}

In this example, we define a custom hook called useFetch that fetches data from a URL and returns it. We use the useDebugValue hook to display a custom debugging message in the React DevTools. If the data is loaded, we display a message that includes the number of items in the data. If the data is still loading, we display a message that says "Loading...".

When you use the useFetch hook in a component, the custom debugging message will be displayed in the React DevTools. This can help you understand what's happening behind the scenes and debug any issues that might arise.

Note that the useDebugValue hook should only be used for debugging purposes and should not affect the behavior of your custom hook. It's a great tool to have in your debugging toolbox when working with custom hooks.