Have you ever come across a website or app that loads and displays more content as you scroll? This is what we call an infinite scroll.
Infinite scroll is a popular technique that reduces the number of page loads. It can also make for a smoother user experience, especially on mobile devices.
There are a few different ways that you can implement infinite scroll in React.js. One way is to use a library like react-infinite-scroll-component. This library provides a component that will trigger an event when the user scrolls to the bottom of the page. You can then use this event to load more content.
Another way to implement infinite scroll is to use the built-in functions that React provides. One such function is “componentDidMount” which React calls when a component is first mounted.
You can use this function to load the first batch of data and then use the “componentDidUpdate” function to load more data when the user scrolls down. You can also use React hooks to add an infinite scrolling feature.
To use react-infinite-scroll-component, you need to install it first using npm:
npm install react-infinite-scroll-component Then, you can import it into your React component.
import React from 'react'
import InfiniteScroll from 'react-infinite-scroll-component'class App extends React.Component {
constructor()
super()
this.state =
items: [],
hasMore: true
componentDidMount()
this.fetchData(1)
fetchData = (page) =>
const newItems = []
for (let i = 0; i < 100; i++)
newItems.push(i )
if (page === 100)
this.setState( hasMore: false )
this.setState( items: [...this.state.items, ...newItems] )
render()
return (
<div>
<h1>Infinite Scroll</h1>
<InfiniteScroll
dataLength=this.state.items.length
next=this.fetchData
hasMore=this.state.hasMore
loader=<h4>Loading...</h4>
endMessage=
<p style= textAlign: 'center' >
<b>Yay! You have seen it all</b>
</p>
>
this.state.items.map((item, index) => (
<div key=index>
item
</div>
))
</InfiniteScroll>
</div>
)
}
export default App
This code starts by importing React and the InfiniteScroll component from the react-infinite-scroll-component library. It then creates a stateful component and initializes the state with an empty items array and a hasMore flag set to true.
In the componentDidMount lifecycle method, you call the fetchData method with a page parameter of 1. The fetchData method makes an API call to get some data. This example just generates some dummy data. It then creates an array of 100 items.
If the page parameter is 100, there are no more items, so set the hasMore flag to false. This will stop the InfiniteScroll component from making further API calls. Finally, set the state using the new data.
The render method uses the InfiniteScroll component and passes in some props. The dataLength prop is set to the length of the items array. The next prop is set to the fetchData method. The hasMore prop is set to the hasMore flag. The loader prop causes the component to render its contents as a loading indicator. Likewise, it will render the endMessage prop as a message when all the data has finished loading.
There are also other props that you can pass to the InfiniteScroll component, but these are the ones you’ll use most often.
Using Built-In Functions
React also has some built-in methods that you can use to implement infinite scroll.
The first method is componentDidUpdate. React calls this method after its updated a component. You can use this method to check if the user has scrolled to the bottom of the page and, if so, load more data.
The second method is scroll, which React calls when the user scrolls. You can use this method to keep track of the scroll position. If the user has scrolled to the bottom of the page, you can then load more data.
Here’s an example of how you could use these methods to implement infinite scroll:
import React, useState, useEffect from 'react'function App()
const [items, setItems] = useState([])
const [hasMore, setHasMore] = useState(true)
const [page, setPage] = useState(1)
useEffect(() =>
fetchData(page)
, [page])
const fetchData = (page) =>
const newItems = []
for (let i = 0; i < 100; i++)
newItems.push(i)
if (page === 100)
setHasMore(false)
setItems([...items, ...newItems])
const onScroll = () =>
const scrollTop = document.documentElement.scrollTop
const scrollHeight = document.documentElement.scrollHeight
const clientHeight = document.documentElement.clientHeight
if (scrollTop + clientHeight >= scrollHeight)
setPage(page + 1)
useEffect(() =>
window.addEventListener('scroll', onScroll)
return () => window.removeEventListener('scroll', onScroll)
, [items])
return (
<div>
items.map((item, index) => (
<div key=index>
item
</div>
))
</div>
)
export default App
This code uses the useState and useEffect hooks to manage state and side effects.
In the useEffect hook, it calls the fetchData method with the current page. The fetchData method makes an API call to get some data. In this example, you’re just generating some dummy data to demonstrate the technique.
The for loop populates the newItems array with 100 integers. If the page parameter is 100, set the hasMore flag to false. This will stop the InfiniteScroll component from making further API calls. Finally, set the state with the new data.
The onScroll method keeps track of the scroll position. If the user has scrolled to the bottom of the page, you can load more data.
The useEffect hook adds an event listener for the scroll event. When the scroll event fires, it calls the onScroll method.
There are pros and cons to using infinite scroll. It can help to improve the user interface, making for a smoother experience, especially on mobile devices. However, it can also lead to users missing content as they may not scroll down far enough to see it.
It is important to weigh up the pros and cons of the infinite scroll technique before implementing it on your website or app.
Adding infinite scroll to your React.js website or app can help to improve the user experience. With infinite scroll, users don’t have to click to see more content. Using Infinite Scroll in your React.js app can also help to reduce the number of page loads, which can improve performance.
You can also easily deploy your React app to Github pages for free.