Clean up function in React, useEffect

cancelFetchRequest.js

useEffect(() => {
    //create a controller
    let controller = new AbortController();
    (async () => {
      try {
        const response = await fetch(API,
          {
            // connect the controller with the fetch request
            signal: controller.signal,
          },
        );
        // handle success
        setList(await response.json());
        // remove the controller
        controller = null;
      } catch (e) {
        // Handle the error
      }
    })();
    //aborts the request when the component umounts
    return () => controller?.abort();
},[]);