use-io.js

function useIO( fun, condition = [] ) {
    // Counter of open I/O requests. If it's 0, I/O is completed.
    // Counter is needed to handle the situation when the next request
    // is issued before the previous one was completed.
    const $isReady = useSafeLink( null );

    useEffect(()=>{
        // function in set instead of value to avoid race conditions with counter increment.
        $isReady.set( x => ( x || 0 ) + 1 );

        fun().finally(() => $isReady.set( x => x - 1 ));
    }, condition);

    // null is used to detect the first render when no requests issued yet
    // but the I/O is not completed.
    return $isReady.value === null ? false : !$isReady.value;
}