Echo

Echo is a standalone JavaScript lazy-loading image tool. Echo is fast, less than 1KB and uses HTML5 data-* attributes. Check out a demo. Echo works in IE8+.

bower install echojs

Using Echo.js is simple, just add the image you wish to load to a data-echo attribute.

<body>

  <img src="img/blank.gif" alt="Photo" data-echo="img/photo.jpg">
  
  <script src="dist/echo.js"></script>
  <script>
  Echo.init({
    offset: 100,
    throttle: 250
  });

  // Echo.render(); is also available for non-scroll callbacks
  </script>
</body>

.init() API (options)

The init() API takes a few options

offset

Type: Number|String Default: 0

The offset option allows you to specify how far below the viewport you want Echo to begin loading your images. If you specify 0, Echo will load your image as soon as it is visible in the viewport, if you want to load 1000px below the viewport, use 1000.

throttle

Type: Number|String Default: 250

The throttle is managed by an internal function that prevents performance issues from continuous firing of window.onscroll events. Using a throttle will set a small timeout when the user scrolls and will keep throttling until the user stops. The default is 250 milliseconds.

.render() API

Echo's callback render() can be used to make Echo poll your images when you're not scrolling, for instance if you've got a filter layout that swaps images but does not scroll, you need to call the internal functions without scrolling. Use render() for this:

Echo.render();

Using render() is also throttled, which means you can bind it to a window.onresize event and it will be optimised for performance in the same way window.onscroll is.

Manual installation

Drop your files into your required folders, make sure you're using the file(s) from the dist folder, which is the compiled production-ready code. Ensure you place the script before the closing </body> tag so the DOM tree is populated when the script runs.

Configuring Echo

Add the image that needs to load when it's visible inside the viewport in a data-echo attribute:

<img src="img/blank.gif" alt="Photo" data-echo="img/photo.jpg">

Scaffolding

Project files and folder structure.

├── dist/
│   ├── echo.js
│   └── echo.min.js
├── src/
│   └── echo.js
├── .editorconfig
├── .gitignore
├── .jshintrc
├── .travis.yml
├── Gruntfile.js
└── package.json

License

MIT license

halkibsi / echo