React Hook Warnings for async function in useEffect: useEffect function must return a cleanup function or nothing

If you’ve been working with React hooks, you might have encountered the following warning message:

    
      Warning: useEffect function must return a cleanup function or nothing.
    
  

This warning typically occurs when using an async function inside the useEffect hook. In this blog post, we will explore two solutions to resolve this warning.

Solution 1: Using an IIFE (Immediately Invoked Function Expression)

One way to handle this warning is by using an IIFE to wrap the async function inside the useEffect hook. This allows us to call the async function immediately and return the cleanup function or nothing as required by the useEffect hook.

    
      useEffect(() => {
        (async () => {
          // Your async function logic here
        })();
        
        return () => {
          // Cleanup logic here
        };
      }, []);
    
  

By wrapping the async function inside an IIFE, we ensure that the useEffect hook receives a cleanup function or nothing as expected.

Solution 2: Using a separate function

Another approach to resolve this warning is by defining a separate function outside the useEffect hook and calling it inside the hook. This allows us to keep the async function separate from the useEffect hook and return the cleanup function or nothing as required.

    
      const fetchData = async () => {
        // Your async function logic here
      };
      
      useEffect(() => {
        fetchData();
        
        return () => {
          // Cleanup logic here
        };
      }, []);
    
  

By defining the async function separately, we can keep the useEffect hook clean and focused on its purpose, while still resolving the warning.

Conclusion

React Hook Warnings for async function in useEffect can be resolved by either using an IIFE or a separate function. Both approaches ensure that the useEffect hook receives a cleanup function or nothing as required.

Remember to choose the solution that best fits your code structure and requirements. Happy coding!