React Lazy Load Component

React Lazy Load is an easy-to-use React component which helps you defer loading content in predictable way. It's fast, You can also use component inside scrolling container, such as div with scrollbar. It will be found automatically. Check out an example.

4.0 Update

Converted to work with React 18, and updated to use the Intersection Observer API.

Breaking changes

• No more debunce, or throttle options as they aren't needed
• Removed individual offset props, offset can be used just like css margin, eg. offset={'0px 10px 200px 0px'} or offset={100}

Improvements

Since we're now using the intersection observer we don't need to watch a user scroll, more importantly we don't have to manually calculate if a user can see the element or not. Also took this oppourtunity to convert over to TS.

Installation

React Lazy Load requires React 17 or later.

npm i -S react-lazy-load

Examples

• In Repo

Examples

Basic Usage

import React from 'react';
import LazyLoad from 'react-lazy-load';

const MyComponent = () => (
  <div>
    <LazyLoad height={762}>
      <img src='http://apod.nasa.gov/apod/image/1502/HDR_MVMQ20Feb2015ouellet1024.jpg' />
    </LazyLoad>
  </div>
)

Loading the image 300px prior to scroll

const MyComponent = () => (
  <div>
    <LazyLoad height={762} offset={300}>
      <img src='http://apod.nasa.gov/apod/image/1502/HDR_MVMQ20Feb2015ouellet1024.jpg' />
    </LazyLoad>
  </div>
)

Loading image only when 95% of it is in the viewport. note a width must be specified.

const MyComponent = () => (
  <div>
    <LazyLoad height={762} width={400} threshold={0.95}>
      <img src='http://apod.nasa.gov/apod/image/1502/HDR_MVMQ20Feb2015ouellet1024.jpg' />
    </LazyLoad>
  </div>
)

Performing a side effect once your image is loaded

const MyComponent = () => (
  <div>
    <LazyLoad height={762} width={400} threshold={0.95} onContentVisible={() => {console.log('loaded!')}}>
      <img src='http://apod.nasa.gov/apod/image/1502/HDR_MVMQ20Feb2015ouellet1024.jpg' />
    </LazyLoad>
  </div>
)

Example controlling element transition

There are two primary classes you an use to control the component LazyLoad and is-visible

/* Example of how to fade our content in */

.LazyLoad {
  opacity: 0;
  transition: all 1s ease-in-out;
}

.is-visible {
  opacity: 1;
}

Props

offset

Type: Number|String Default: 0

The offset option allows you to specify how far below, above, to the left, and to the right of the viewport you want to begin displaying your content. If you specify 0, your content will be displayed as soon as it is visible in the viewport, if you want to load 1000px below or above the viewport, use 1000.

threshold

Type: Number Default: 0

This threshold option allows you to specify how much of the element must be shown on the screen prior to loading. This requires a width and height to be set on the <LazyLoad> component in order for the browser to calcualte the viewable area.

height

Type: String|Number

The height option allows you to set the element's height even when it has no content.

width

Type: String|Number

The width option allows you to set the element's width even when it has no content.

onContentVisible

Type Function

A callback function to execute when the content appears on the screen.

Building LazyLoad

npm run build

Running examples

cd examples/basic
npm run dev