在 useEffect 中无法获取当前道具

Question

I use useEffect with parameter props.quizStep . But fn (keydown event listener function) cannot get current props.quizStep .

Why it cannot get current props?

Here is my code.

    const moveBirdKeyboard = React.useEffect(() => {
        console.log('moveBirdKeyboard props.quizStep', props.quizStep);
        let fn = (e: any) => {
            console.log('props.quizStep', props.quizStep);
            moveBirdEvent(e);
        }
        if(eventListener.current === false) {
            (window as any).addEventListener('keydown', _.throttle(fn,10)); //_.throttle(fn,1000));
            eventListener.current = true;
        } 
    }, [props.quizStep]);

Answer 1

You cannot assign the useEffect hook to a variable, as it says its a hook, not a property. Instead of that you need to create a function which properties can be attached to a hook.

A good example from the reactJS documentation:

function Example() {
  const [count, setCount] = useState(0);
  useEffect(() => {
    document.title = `Clicked ${count} times`;
  });