Listens for changes in the pressed state of a given key.
- Use the
useState()
hook to create a state variable that holds the pressed state of the given key. - Define two handler functions that update the state variable on key down or key up accordingly.
- Use the
useEffect()
hook andEventTarget.addEventListener()
to handle the'keydown'
and'keyup'
events. - Use
EventTarget.removeEventListener()
to perform cleanup after the component is unmounted.
代码实现
const useKeyPress = targetKey => {
const [keyPressed, setKeyPressed] = React.useState(false);
const downHandler = ({ key }) => {
if (key === targetKey) setKeyPressed(true);
};
const upHandler = ({ key }) => {
if (key === targetKey) setKeyPressed(false);
};
React.useEffect(() => {
window.addEventListener('keydown', downHandler);
window.addEventListener('keyup', upHandler);
return () => {
window.removeEventListener('keydown', downHandler);
window.removeEventListener('keyup', upHandler);
};
}, []);
return keyPressed;
};
使用样例
const MyApp = () => {
const wPressed = useKeyPress('w');
return <p>The "w" key is {!wPressed ? 'not ' : ''}pressed!</p>;
};
ReactDOM.createRoot(document.getElementById('root')).render(
<MyApp />
);