Infinite scroll - Infinite scrolling allows content to load continuously as the user moves down the page, unlike the click-to-load method of traditional page alignment. This feature can provide a smoother experience, especially on mobile devices.

How to implement Infinite Scroll in web application Picture 1

Let's explore with TipsMake how to set up simple Infinite scroll using HTML, CSS and JavaScript !

Set up the frontend

Start with basic HTML structure to display content. Here is an example:

Page scrolls infinitely

This page contains a string of placeholder images and references two sources: a CSS file and a JavaScript file.

CSS styles for scrollable content

To display the placeholder image in a grid, add the following CSS to the style.css file :

* { margin: 0; padding: 0; box-sizing: border-box; } html { font-size: 62.5%; } body { font-family: Cambria, Times, "Times New Roman", serif; } h1 { text-align: center; font-size: 5rem; padding: 2rem; } img { width: 100%; display: block; } .products__list { display: flex; flex-wrap: wrap; gap: 2rem; justify-content: center; } .products__list > * { width: calc(33% - 2rem); } .loading-indicator { display: none; position: absolute; bottom: 30px; left: 50%; background: #333; padding: 1rem 2rem; color: #fff; border-radius: 10px; transform: translateX(-50%); } 

Currently, your page will look like this:

How to implement Infinite Scroll in web application Picture 2

Core implementation with JS

Edit script.js. To implement infinite scroll, you need to detect when the user has scrolled near the bottom of the container or content page.

"use strict"; window.addEventListener("scroll", () => { if ( window.scrollY + window.innerHeight >= document.documentElement.scrollHeight - 100 ) { // Người dùng ở gần dưới cùng, tìm nạp nhiều nội dung hơn fetchMoreContent(); } });

Then create a function to fetch more placeholder data.

async function fetchMoreContent() { try { let response = await fetch("https://fakestoreapi.com/products?limit=3"); if (!response.ok) { throw new Error("Network response was not ok"); } let data = await response.json(); console.log(data); } catch (error) { console.error("There was a problem fetching new content:", error); } finally { console.log("Fetch function fired"); } } 

For this project, you can use the API from fakestoreapi .

To confirm data is fetched on scroll, look at the console:

How to implement Infinite Scroll in web application Picture 3

You will see the data fetched multiple times as you scroll. It may be a factor affecting the performance of the device. To avoid this, create an initial data fetch state:

let isFetching = false;

Then, edit the fetch function to only find data after a previously completed process.

async function fetchMoreContent() { if (isFetching) return; // Thoát nếu tìm nạp dữ liệu đã xong isFetching = true; // Đặt flag sang true try { let response = await fetch("https://fakestoreapi.com/products?limit=3"); if (!response.ok) { throw new Error("Network response was not ok"); } let data = await response.json(); } catch (error) { console.error("There was a problem fetching new content:", error); } finally { console.log("Fetch function fired"); isFetching = false; // Reset flag sang false } }

Show new content

To show new content when the user scrolls down the page, create a function that appends the images to the main container.

First, choose the main component:

const productsList = document.querySelector(".products__list");

Then create a function that appends content:

function displayNewContent(data) { data.forEach((item) => { const imgElement = document.createElement("img"); imgElement.src = item.image; imgElement.alt = item.title; productsList.appendChild(imgElement); // Append to productsList container }); } 

Finally, edit the fetch function and pass the fetched data to the append function.

async function fetchMoreContent() { if (isFetching) return; isFetching = true; try { let response = await fetch("https://fakestoreapi.com/products?limit=3"); if (!response.ok) { throw new Error("Network response was not ok"); } let data = await response.json(); displayNewContent(data); } catch (error) { console.error("There was a problem fetching new content:", error); } finally { console.log("Fetch function fired"); isFetching = false; } } 

That's it, infinite scrolling will now work.

How to implement Infinite Scroll in web application Picture 4

Enhance infinite scrolling

To enhance user experience, you can display a loading indicator when fetching new content. Start by adding this HTML.

Loading.

Then select the loading component.

const loadingIndicator = document.querySelector(".loading-indicator");

Finally, create two functions that enable/disable loading indicator visibility.

function showLoadingIndicator() { loadingIndicator.style.display = "block"; console.log("Loading."); } function hideLoadingIndicator() { loadingIndicator.style.display = "none"; console.log("Finished loading."); } 

Then add them to the fetch function.

async function fetchMoreContent() { if (isFetching) return; // Exit if already fetching isFetching = true; showLoadingIndicator(); // Show loader try { let response = await fetch("https://fakestoreapi.com/products?limit=3"); if (!response.ok) { throw new Error("Network response was not ok"); } let data = await response.json(); displayNewContent(data); } catch (error) { console.error("There was a problem fetching new content:", error); } finally { console.log("Fetch function fired"); hideLoadingIndicator(); // Hide loader isFetching = false; } }

Result:

How to implement Infinite Scroll in web application Picture 5

Things to note when using infinite scroll:

1. Don't fetch too many items at once as it may reduce browser performance.
2. Instead of fetching content immediately after detecting a scroll event, use a debug function to delay the fetch a bit. This can prevent excessive network queries.
3. Not all users like infinite scrolling. Provide the option to use a pagination component if desired.

If there isn't much content left to load, notify the user instead of constantly trying to fetch more data.

Lesley Montoya

Update 09 November 2023