Implementing Infinite scroll in React apps

Infinite scroll is a technique that loads content continuously as the user scrolls down the page, eliminating the need for pagination. This approach can enhance user engagement and time spent on the site, making it a popular choice for social media platforms and content-heavy applications. This blog aims to guide React developers through the implementation of infinite scroll in their applications using the react-infinite-scroll-component library.

Understanding the basics

Infinite scroll works by triggering an event as the user approaches the bottom of the content. This event initiates a request to fetch more content, which is then appended to the existing content. Unlike pagination, which divides content into discrete pages, infinite scroll offers a fluid, uninterrupted browsing experience.

Setting up the project

Start by creating a new React project using Vite:

npm create vite@latest

After setting up the project, install the react-infinite-scroll-component library:

npm i react-infinite-scroll-component

Install the axios library to make API requests:

npm install axios

Implementing infinite scroll

We will be using the Rick and Morty API to demonstrate infinite scroll. We will be fetching characters from the API on an infinite scroll event and displaying them in a list of cards.

I'll be using Material UI for styling the cards. You can install it by visiting the Material UI installation guide.

Let's start by creating a basic CharacterCard component:

import Card from "@mui/material/Card";
import CardHeader from "@mui/material/CardHeader";
import Avatar from "@mui/material/Avatar";

export default function CharacterCard({ character }) {
  return (
    <Card
      sx={{
        maxWidth: 345,
        background: "black",
        color: "white",
        margin: "10px",
        borderRadius: "10px",
      }}
    >
      <CardHeader
        avatar={<Avatar src={character?.image} aria-label="recipe"></Avatar>}
        title={character?.name}
        subheader={`Status: ${character?.status}`}
      />
    </Card>
  );
}

Next, in your App.js file, implement the infinite scroll functionality:

• We will be defining a few states for our characters, pages, the totalPageCount and a boolean state to determine if we need to fetch more characters.

const [characters, setCharacters] = useState([]);
const [page, setPage] = useState(1);
const [hasMore, setHasMore] = useState(true);
const [totalPages, setTotalPages] = useState(1);

Here, characters will store the fetched characters, page will keep track of the current page number, hasMore will determine if there are more characters to fetch, and totalPages will store the total number of pages.

We will initialize totalPages by 1 initially and then after each subsequent call, we will update the state with the value from the API response.

• Next, we will define a function fetchData to fetch characters from the API:

const fetchData = async () => {
  if (page == totalPages + 1) {
    setHasMore(false);
    return;
  }

  // <----------------------------------------------->

  // waiting for 1 second before fetching data to show loading spinner, you can skip this
  await new Promise((resolve) => setTimeout(resolve, 1000));

  // <----------------------------------------------->

  const res = await axios.get(
    `https://rickandmortyapi.com/api/character?page=${page}`
  );
  setCharacters((prevPosts) => [...prevPosts, ...res.data.results]);
  setTotalPages(res.data.info.pages);
  setPage((prevPage) => prevPage + 1);
};

Here, we are fetching characters from the API and appending them to the characters state. We are also updating the totalPages and page states accordingly.

I am adding a delay of 1 second before fetching data to show the loading state properly and better understand the infinite scroll functionality. You can skip this if you want.

We will stop fetching data when the page reaches the totalPages + 1. At this point, we will set hasMore to false.

• Finally, we will implement the InfiniteScroll component:

<InfiniteScroll
  dataLength={characters.length}
  next={fetchData}
  hasMore={hasMore}
  loader={<h4>Loading...</h4>}
  endMessage={
    <p>
      <b>Yay! You have seen it all</b>
    </p>
  }
>
  {/* Map over characters array and return JSX */}
  {characters.map((character, index) => (
    <CharacterCard key={index} character={character} />
  ))}
</InfiniteScroll>

The InfiniteScroll component takes the following props:

• dataLength: we set the length of data to determine when to trigger the next function.
• next: the function to call when the user scrolls to the bottom of the page.
• hasMore: a boolean value to determine if there is more data to fetch.
• loader: a loading spinner to display while fetching data.
• endMessage: a message to display when all data has been fetched.

We can also add some extra props to the InfiniteScroll component to customize the behavior according to our requirements. You can read more about the react-infinite-scroll-component library here.

• Next, we will call the fetchData function when the component mounts:

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

This will fetch the initial set of characters when the component mounts.

• App.js should look something like this:

import { useEffect, useState } from "react";
import axios from "axios";
import "./App.css";
import InfiniteScroll from "react-infinite-scroll-component";
import CharacterCard from "./components/Card";

function App() {
  const [characters, setCharacters] = useState([]);
  const [page, setPage] = useState(1);
  const [hasMore, setHasMore] = useState(true);
  const [totalPages, setTotalPages] = useState(1);

  const fetchData = async () => {
    if (page == totalPages + 1) {
      setHasMore(false);
      return;
    }

    // <----------------------------------------------->

    // waiting for 1 second before fetching data to show loading spinner, you can skip this
    await new Promise((resolve) => setTimeout(resolve, 1000));

    // <----------------------------------------------->

    const res = await axios.get(
      `https://rickandmortyapi.com/api/character?page=${page}`
    );
    setCharacters((prevPosts) => [...prevPosts, ...res.data.results]);
    setTotalPages(res.data.info.pages);
    setPage((prevPage) => prevPage + 1);
  };

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

  return (
    <div
      style={{
        display: "flex",
        justifyContent: "center",
        flexDirection: "column",
        alignItems: "center",
      }}
    >
      <h1>Rick and Morty characters!</h1>
      <InfiniteScroll
        dataLength={characters.length} 
        next={fetchData}
        hasMore={hasMore}
        loader={<h4>Loading...</h4>}
        endMessage={
          <p>
            <b>Yay! You have seen it all</b>
          </p>
        }
      >
        {/* Map over characters array and return JSX */}
        {characters.map((character, index) => (
          <CharacterCard key={index} character={character} />
        ))}
      </InfiniteScroll>
    </div>
  );
}

export default App;

We are now ready to test the infinite scroll functionality in our React application. Run the project using npm run dev and scroll down to see the infinite scroll in action. You should see something like this:

Conclusion

Infinite scroll is a powerful technique that can enhance user experience by providing a seamless browsing experience. By implementing infinite scroll in your React applications, you can create engaging and dynamic user interfaces that keep users coming back for more. The react-infinite-scroll-component library simplifies the process of implementing infinite scroll, making it easy for developers to add this feature to their applications. I hope this guide helps you get started with infinite scroll in your React projects. Happy coding!