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

Decoding async operations within useEffect

Let's properly handle async code within useEffect. By chiseling out a separate async function and invoking it within useEffect, the code stays uncluttered and adheres to React's lifecycle conventions.

Believe in magic: IIFE within useEffect

Immediately-Invoked Function Expression (IIFE) is our broomstick for a swift ride:

useEffect(() => {
  (async () => {
    try {
      const result = await someAsyncOperation(); // We have lift off! 🚀
      // Handle the Martian rock (result)
    } catch (error) {
      // In case of UFOs (errors)
    }
  })();
}, []);
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Get out of Hogwarts clean and ready for the ball, having sorted proper cleanup for this async charm.

The new dawn: Suspense for data fetching

React 18's Suspense for data fetching signals the future where effects might be less significant for data fetch. Libraries like swr work with Suspense, providing a seamless way to fetch data, taking care of caching, revalidation, and error handling.

Channeling the force of async operations

The real challenge lies when your useEffect hook houses async code. The mission is to ensure async tasks exit cleanly if your component unmounts. Managing listeners for data fetching properly makes the force strong with your useEffect.

Tidy up your spaceship

To prevent alien parasites (memory leaks) and black holes (side effects), you must cancel pending fetch requests when components disassemble. Fetch API's signal option and the AbortController are great space guns:

useEffect(() => {
  const abortController = new AbortController();
  const fetchData = async () => {
    try {
      const response = await fetch(url, { signal: abortController.signal });
      const data = await response.json();
      // Toast to fetched data 🍾
    } catch (error) {
      if (error.name !== 'AbortError') {
        // Handle non-aborted fetch error
      }
    }
  };

  fetchData();
  return () => abortController.abort(); // Call off the search party on unmount
}, []); 
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Jedi Hooks: Leverage for memoization

For the light to stay strong against frequently changing dependencies, the use of useCallback helps memoize functions to limit re-invocations. Whether passing callbacks to child components or running heavy-duty operations within useEffect, useCallback is the Jedi way.

Charting the future

Though Suspense for data fetching isn't a fully bloomed flower yet, it's prudent to keep tabs and experiment with soon-to-be-popular trends in the React universe. Supporting libraries like swr or building your own custom hooks like useEffectAsync can help manage async processes within useEffect.