d-lazyimg

Lazy load images

Dependencies

Requires derby-stylus to support styles.

Usage

1. Create images.assets.js file with datauri images. Use datauri module for it:

   // File must be named *.assets.js
   var datauri = require('datauri');
   
   module.exports = {
   
     // Logo (full versions to be used with dataimg)
     '/img/logo_blue.svg': datauri(
         __dirname + '/../public/img/logo_blue.svg'),
   
     '/img/logo_white.svg': datauri(
         __dirname + '/../public/img/logo_white.svg'),    
   
     // Backgrounds (we specify minified versions to be used with lazyimg)
   
     '/img/cloudy-hills.jpg': datauri(
         __dirname + '/../public/img/cloudy-hills.min.jpg'),
     '/img/bg_strings.jpg': datauri(
         __dirname + '/../public/img/bg_strings.min.jpg'),
   };

2. Plug in d-lazyimg module and provide datauri assets as an option:

   app.use(require('d-lazyimg'), require('./images.assets'));

3. Use lazyimg component to do lazy loading of big image:

   <lazyimg img='/img/cloudy-hills.jpg'>

It will instantly load the small image cloudy-hills.min.jpg you specified in the assets as datauri. Right after that it will start the regular asynchronous loading of the heavy cloudy-hills.jpg. When full image finish loading it will transparently switch itself with the minified version.

Image caching is not affected - if the full image is already in the browser's cache it won't try to load it the second time the server.

4. Use dataimg to embed the full image as datauri:

   <dataimg img='/img/logo_blue.svg'>