38 lines
1.1 KiB
Markdown
38 lines
1.1 KiB
Markdown
---
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title: React useOnWindowScroll hook
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tags: hooks,effect,event
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author: chalarangelo
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cover: planning
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firstSeen: 2021-12-08T05:00:00-04:00
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---
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Executes a callback whenever the window is scrolled.
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- Use the `useRef()` hook to create a variable, `listener`, which will hold the listener reference.
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- Use the `useEffect()` hook and `EventTarget.addEventListener()` to listen to the `'scroll'` event of the `Window` global object.
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- Use `EventTarget.removeEventListener()` to remove any existing listeners and clean up when the component unmounts.
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```jsx
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const useOnWindowScroll = callback => {
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const listener = React.useRef(null);
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React.useEffect(() => {
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if (listener.current)
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window.removeEventListener('scroll', listener.current);
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listener.current = window.addEventListener('scroll', callback);
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return () => {
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window.removeEventListener('scroll', listener.current);
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};
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}, [callback]);
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};
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```
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```jsx
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const App = () => {
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useOnWindowScroll(() => console.log(`scroll Y: ${window.pageYOffset}`));
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return <p style={{ height: '300vh' }}>Scroll and check the console</p>;
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};
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ReactDOM.render(<App />, document.getElementById('root'));
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```
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