diff --git a/snippets/useKeyPress.md b/snippets/useKeyPress.md new file mode 100644 index 000000000..5fdcdd33a --- /dev/null +++ b/snippets/useKeyPress.md @@ -0,0 +1,48 @@ +--- +title: useKeyPress +tags: hooks,state,effect,intermediate +firstSeen: 2021-09-07T05:00:00-04:00 +--- + +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 and `EventTarget.addEventListener()` to handle the `'keydown'` and `'keyup'` events. +- Use `EventTarget.removeEventListener()` to perform cleanup after the component is unmounted. + +```jsx +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; +}; +``` + +```jsx +const MyApp = () => { + const wPressed = useKeyPress('w'); + + return

The "w" key is {!wPressed ? 'not ' : ''}pressed!

; +}; + +ReactDOM.render(, document.getElementById('root')); +```