How to use the React setState hook from scroll event listener?

Estimated read time 2 min read

You can use the React useState hook to update the state of your component from a scroll event listener. Here’s an example:

import React, { useState, useEffect } from 'react';

function MyComponent() {
  const [scrollPosition, setScrollPosition] = useState(0);

  useEffect(() => {
    function handleScroll() {
      const position = window.pageYOffset;
      setScrollPosition(position);
    }

    window.addEventListener('scroll', handleScroll);

    return () => {
      window.removeEventListener('scroll', handleScroll);
    };
  }, []);

  return (
    <div>
      <p>Scroll position: {scrollPosition}</p>
      {/* rest of your component code */}
    </div>
  );
}

In this example, we define a component called MyComponent that uses the useState hook to keep track of the scroll position. We use the useEffect hook to add a scroll event listener to the window object. The handleScroll function is called every time the user scrolls, and it updates the scrollPosition state with the current scroll position. We also use the useEffect hook to remove the event listener when the component unmounts.

Note that we pass an empty array ([]) as the second argument to the useEffect hook. This ensures that the effect is only run once, when the component mounts. If you want to update the state when a certain prop or state value changes, you can pass it as a dependency in the array.

You can use the setState hook to update any state value in your component from a scroll event listener or any other event listener. Just define a function to handle the event, update the state with the setState hook, and attach the event listener to the appropriate DOM element.

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