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    react-lazyloading-images

    3.0.1 • Public • Published

    react-lazyloading-images

    Lazy loading image component for React

    The main goal of this component is providing reliable, performance optimized, cross-browser, responsive and SEO friendly lazyloading images. It supports WebP image format for Google Chrome and Android and JPEG or PNG for other browsers. It means you need to provide both image formats, accessible from your public directory. This component allows you to implement blurry low quality image placeholder technic, which Medium.com uses.

    WebP is widely supported by Chrome and Android browsers according to https://caniuse.com/#feat=webp and it is much lighter format than any other image standard. Firefox and Safari are working on their implementation.

    You can provide breakpoints array with objects, to serve smaller images for mobile users and bigger images for desktop users. You can orchestrate unique user experience by providing variable images, depending on user device.

    1. Install

    npm i -S react-lazyloading-images
    

    or

    yarn add react-lazyloading-images
    

    2. Examples

    You can use LazyImage component in two ways, Basic and Advanced

    import LazyImage from 'react-lazyloading-images'
    
    const BasicLazyImage = () => (
        <LazyImage
        path='/images/logo.{png|jpe?g}' // type: String, if breakpoints array provided - optional
        blur='/images/logo-blur.{png|jpe?g}' // type: String, if breakpoints array provided - optional,
        width=100 // type: number, if breakpoints array provided - optional. default value 48,
        height=100 // type: number, if breakpoints array provided - optional. default value 48,
            className='lazyImage' // type: String, optional, default value === ''
        title='logo' // type: String, optional, default value === ''
            alt='logo' // type: String, required.
        />
    )
    
    const AdvancedLazyImage = () => (
        <LazyImage
            className='lazyImage' // type: String, optional, default value === ''
        title='logo' // type: String, optional, default value === ''
            alt='logo' // type: String, required.
            breakpoints={[
          {
            media: '(max-width: 767px)', // type: String
            path: '/img/logo-mobile.jpeg', // type: String
            blur: '/img/logo-mobile-blur.jpeg', // type: String
            width: 50, // type: Number,
            height: 50 // type: Number
          },
          {
            media: '(min-width: 768px) and (max-width: 1279px)',  // type: String
            path: '/img/logo-tablet.jpeg',  // type: String
            blur: '/img/logo-tablet-blur.jpeg',  // type: String
            width: 75, // type: Number,
            height: 75 // type: Number
          },
          {
            media: '(min-width: 1280px)',
            path: '/img/logo-desktop.jpeg',
            blur: '/img/logo-desktop-blur.jpeg',
            width: 100, // type: Number,
            height: 100 // type: Number
          }
        ]} // optional.
        style={{ width: '100%', height: 'auto' }} // type: object, optional
            rootMargin='500px 0px' // type: String, optional, default value === '300px 0px'
        />
    )
    

    3. Important information:

    Under the hood Lazy loading made with IntersectionObserver API and uses npm intersection-observer polyfill as fallback.

    media prop should be compatible with Window.matchMedia API https://developer.mozilla.org/en-US/docs/Web/API/Window/matchMedia

    4. Additional information:

    You can use Gulp and gulp plugins to generate highly optimized PNG and WEBP assets.

    I highly recommend you to use code below in separate directory from your main project, and copy results to your public directory, or if you want to use it in your own project, modify src and dist.

    First thing you need to do is install gulp and several plugins:

    npm i -D gulp gulp-webp gulp-imagemin gulp-rename gulp-image-resize
    
    Mac OS
    brew install imagemagick
    brew install graphicsmagick
    
    Linux
    apt-get install imagemagick
    apt-get install graphicsmagick
    
    Windows
    http://www.imagemagick.org/script/binary-releases.php
    

    Next step is gulpfile.js in the root directory, and make src and dest directories:

    mkdir src && mkdir dest
    

    gulpfile.js content:

    const gulp = require('gulp')
    const rename = require('gulp-rename')
    const imagemin = require('gulp-imagemin')
    const imageResize = require('gulp-image-resize')
    const webp = require('gulp-webp')
    
    const config = {
      placeholderSize: 48,
      src: 'src/*.{png|jpe?g}',
      dest: 'dest/',
      outputFormat: 'png',
      webp: false,
    }
    
    gulp.task('minify', () =>
      gulp
        .src(config.src)
        .pipe(imagemin({ progressive: true, verbose: true, optimizationLevel: 5 }))
        .pipe(gulp.dest(config.dest))
    )
    
    gulp.task('placeholder', () =>
      gulp
        .src(config.src)
        .pipe(imageResize({ width : config.placeholderSize, format: config.outputFormat }))
        .pipe(rename({ suffix: '-placeholder', dirname: '' }))
        .pipe(gulp.dest(config.dest))
    )
    
    gulp.task('webp', () =>
      gulp
        .src(config.src)
        .pipe(imagemin({ progressive: true, verbose: true, optimizationLevel: 5 }))
        .pipe(webp())
        .pipe(gulp.dest(config.dest))
    )
    
    gulp.task('default', ['minify', 'placeholder', 'webp'])
    

    Paste your png files to src directory and run:

    gulp
    

    For each source image you will get 3 asset images. For example if you provide logo.png in /src/, you will get production optimized logo.png, logo.webp and logo-placeholder.png.

    You need to copy all 3 files to your ./public/ directory, and specify relative path prop for <LazyImage /> without suffix and extension. Suffix will be generated for free.

    If your images path is /public/images/logo.png, you need to set path prop as in example below:

    <LazyImage
      path='/images/logo.jpg'
      blur='/images/logo-blur.jpg'
      width=100
      height=100
      alt='logo'
    />
    

    You can provide any other attributes as props, and it will be set to <img /> tag.

    For WebP suport detection, you can import boolean value isWebPSupported from the package.

    import { isWebPSupported } from 'react-lazyloading-images'
    

    If you have any questions or ideas how to improve the package, please make an issue in github repository. https://github.com/JustFly1984/react-lazyload-image/issues

    Install

    npm i react-lazyloading-images

    DownloadsWeekly Downloads

    19

    Version

    3.0.1

    License

    MIT

    Unpacked Size

    75.8 kB

    Total Files

    9

    Last publish

    Collaborators

    • justfly1984