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Infinite Scroll

Pablo Romera foto

Pablo Romera 

/

 October 20, 2023 / 3 min read

Pablo Romera foto

Building an Infinite Scroll in React from Scratch

Unlock the secrets of implementing an infinite scroll in React. Dive into our step-by-step guide covering everything from setup to advanced techniques for seamless scrolling.

Introduction

Are you looking to enhance your React applications with smooth, uninterrupted scrolling experiences? Infinite scrolling is a popular technique used in modern web development, allowing users to continuously scroll through content without the need for pagination. In this article, we'll delve into the intricacies of building an infinite scroll in React from scratch, offering a blend of technical expertise, practical examples, and insightful tips to elevate your skills.

The Foundation: Initial State and Environment Setup

Before diving into the infinite scroll's code, let's set up our React environment and establish the initial state for our infinite scroll component.

Setting Up the Initial State

Every React component thrives on state management, and infinite scrolling is no exception. We'll start by setting up the initial state for our component. This includes initializing an array for the items we'll display, loading and error indicators, and a variable for tracking the current page number. Using React's useState and useEffect hooks, we'll lay the foundation for our infinite scroll functionality.

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

const InfiniteScrollExample = () => {
  const [items, setItems] = useState([]);
  const [isLoading, setIsLoading] = useState(false);
  const [error, setError] = useState(null);
  const [page, setPage] = useState(1);

  // ... rest of the component
};

Infinite Scroll Mechanics

Fetching Data and Managing State

Now, let's focus on the core functionality of our infinite scroll - fetching data and updating the state. We'll create a function to fetch data from an API endpoint. This function will be called each time the user scrolls near the bottom of the page, loading additional content.

Here's a basic example of a data-fetching function in our component:

const fetchData = async () => {
  setIsLoading(true);
  setError(null);

  try {
    const response = await fetch(`https://api.example.com/items?page=${page}`);
    const data = await response.json();

    setItems((prevItems) => [...prevItems, ...data]);
    setPage((prevPage) => prevPage + 1);
  } catch (error) {
    setError(error);
  } finally {
    setIsLoading(false);
  }
};

useEffect(() => {
  fetchData();
}, []);

Building the Infinite Scroll

Extending our basic setup, we’ll first create a function to handle the scroll event. This function will check if the user has reached the bottom of the page and call fetchData if necessary. We’ll add a scroll event listener to the window object and remove it when the component is unmounted:

const handleScroll = () => {
  if (
    window.innerHeight + document.documentElement.scrollTop !==
      document.documentElement.offsetHeight ||
    isLoading
  ) {
    return;
  }
  fetchData();
};

useEffect(() => {
  window.addEventListener("scroll", handleScroll);
  return () => window.removeEventListener("scroll", handleScroll);
}, [isLoading]);

Finally, we render the items, the loading indicator, and any error messages within the component:

return (
  <div>
    <ul>
      {items.map((item) => (
        <li key={item.id}>{item.name}</li>
      ))}
    </ul>
    {isLoading && <p>Loading...</p>}
    {error && <p>Error: {error.message}</p>}
  </div>
);

With that, we have a fully functional infinite scroll implementation built from scratch. This approach allows for extensive customization and more control over functionality. However, it may be more time-consuming and require more maintenance than using an existing library or component.

Conclusion

Infinite scroll is more than just a technical implementation; it's a way to enhance user experience and engagement. By following the guidelines and techniques outlined in this article, you can implement an effective infinite scroll in your React applications, providing users with a seamless and engaging browsing experience.