In this blog post, we will learn how to create a custom React hook called useScrollPositionEffect that will allow us to handle side effects based on the scroll position of the user’s browser window. This can be useful for implementing features such as parallax scrolling, lazy loading, or any other effect that needs to be triggered based on how far the user has scrolled.

Table of Contents

1. Introduction to the useScrollPositionEffect hook
2. Implementing the useScrollPositionEffect hook
3. Using the useScrollPositionEffect hook
4. Conclusion
5. References

Introduction to the useScrollPositionEffect hook

The useScrollPositionEffect hook will help us simplify the logic required to handle side effects based on the scroll position. It will provide us with a callback function that will be called every time the user scrolls, passing the current scroll position as parameters. This will allow us to easily define what should happen when the user scrolls to a specific position.

Implementing the useScrollPositionEffect hook

Let’s start by creating a new file called useScrollPositionEffect.js and defining our custom hook inside it:

import { useEffect } from 'react';

const useScrollPositionEffect = (callback) => {
  useEffect(() => {
    const handleScroll = () => {
      const scrollPosition = window.scrollY;
      callback(scrollPosition);
    };

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

export default useScrollPositionEffect;

In the code above, we are using the useEffect hook to add an event listener for the scroll event. Inside the event listener, we are getting the current scroll position using window.scrollY and calling the provided callback function with this value. We are also using the useEffect hook’s cleanup function to remove the event listener when the component using the hook is unmounted.

Using the useScrollPositionEffect hook

Now that we have implemented our useScrollPositionEffect hook, let’s see how we can use it in a React component. Here’s an example of a component that changes its background color based on the scroll position:

import React from 'react';
import useScrollPositionEffect from './useScrollPositionEffect';

const ScrollColorEffect = () => {
  const handleScroll = (scrollPosition) => {
    // Logic to change background color based on scroll position
    if (scrollPosition > 200) {
      document.body.style.backgroundColor = 'blue';
    } else {
      document.body.style.backgroundColor = 'white';
    }
  };

  useScrollPositionEffect(handleScroll);

  return (
    <div>
      {/* Component content */}
    </div>
  );
};

export default ScrollColorEffect;

In the code above, we define a component called ScrollColorEffect that uses our custom hook. We provide the handleScroll function as the callback to be called when the user scrolls. Inside this function, we change the background color of the document.body based on the scroll position. This is just a simple example, but you can use the same pattern to implement more complex effects.

Conclusion

In this blog post, we have learned how to create a custom React hook called useScrollPositionEffect for handling side effects based on the scroll position. This hook simplifies the logic required to handle scrolling effects and allows us to define what should happen at specific scroll positions. Feel free to customize this hook to fit your specific needs, and happy coding!

References

• React Hooks documentation