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React - scroll stop event

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Created by:
Dirask JS Member
3430

In this short article, we would like to show how to detect scroll stop event ('scroll end event').

The solution for the problem is to use some trick: do some logic when scroll event doesn't occur few milliseconds after appeared.

Note: to make element scrollable we should use one of the overflow style property (e.g. overflowY: 'scroll').

Runnable example:

// ONLINE-RUNNER:browser;

// Note: Uncomment import lines during working with JSX Compiler.
// import React from 'react';
// import ReactDOM from 'react-dom';

const createScrollStopListener = (element, callback, timeout) => {
    let removed = false;
    let handle = null;
    const onScroll = () => {
        if (handle) {
             clearTimeout(handle);
        }
        handle = setTimeout(callback, timeout || 200); // default 200 ms
    };
    element.addEventListener('scroll', onScroll);
    return () => {
        if (removed) {
            return;
        }
        removed = true;
      	if (handle) {
      		clearTimeout(handle);
        }
    	element.removeEventListener('scroll', onScroll);
    };
};

const App = () => {
  	const containerRef = React.useRef();

    React.useEffect(() => {
        const destroyListener = createScrollStopListener(containerRef.current, () => {
            console.log('onscrollstop');
        });
      	return () => destroyListener(); // when App component is unmounted
    }, []);

    return (
      <div ref={containerRef} style={{ height: '200px', overflowY: 'scroll' }}>
        <div style={{ height: '700px', background: 'silver' }}>
          Scroll me up, down, up down and stop!
        </div>
      </div>
    );
};

const root = document.querySelector('#root');
ReactDOM.render(<App />, root);

Window scroll stop event example

We are able to indicate window as scrolled element.

// ONLINE-RUNNER:browser;

// Note: Uncomment import lines during working with JSX Compiler.
// import React from 'react';
// import ReactDOM from 'react-dom';

const createScrollStopListener = (element, callback, timeout) => {
    let removed = false;
    let handle = null;
    const onScroll = () => {
        if (handle) {
             clearTimeout(handle);
        }
        handle = setTimeout(callback, timeout || 200); // default 200 ms
    };
    element.addEventListener('scroll', onScroll);
    return () => {
        if (removed) {
            return;
        }
        removed = true;
      	if (handle) {
      		clearTimeout(handle);
        }
    	element.removeEventListener('scroll', onScroll);
    };
};

const App = () => {
    React.useEffect(() => {
        const destroyListener = createScrollStopListener(window, () => {
            console.log('onscrollstop');
        });
      	return () => destroyListener(); // when App component is unmounted
    }, []);

    return (
      <div style={{ height: '1000px', background: 'silver' }}>
        Scroll me up, down, up down and stop!
      </div>
    );
};

const root = document.querySelector('#root');
ReactDOM.render(<App />, root);
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