react-lazyload

Lazyload your Components, Images or anything matters the performance.

Online Demo

Why it's better

• Take performance in mind, only 2 event listeners for all lazy-loaded components
• Support both one-time lazy load and continuous lazy load mode
• scroll / resize event handler is debounced so you won't suffer with frequent update
• IE 8 compatible

Who should use it

Let's say there is a fixed date picker on the page, when user pick a different date, all components displaying data should send ajax request with new date parameter to retreive updated data, even many of them aren't visible in viewport. This makes server load furious when there are too many requests in one page.

Using LazyLoad component will help ease this situation by only update components in viewport.

Usage

import React from 'react';
import LazyLoad from 'react-lazyload';
import MyComponent from './MyComponent';

const App = React.createClass({
  render() {
    return (
      <div className="list">
        <LazyLoad>
          <MyComponent />
        </LazyLoad>
        <LazyLoad>
          <MyComponent />
        </LazyLoad>
        <LazyLoad once >        /* Once this component is loaded, LazyLoad will
                                   not care about it anymore, stuff like images
                                   should add `once` props to reduce listeners for
                                   scroll/resize event and improve performance */
          <MyComponent />
        </LazyLoad>
        <LazyLoad offset={100}> /* This component will be loaded when it's top
                                   edge is 100px from viewport. It's useful to
                                   make user ignorant about lazy load effect. */
          <MyComponent />
        </LazyLoad>
        <LazyLoad>
          <MyComponent />
        </LazyLoad>
      </div>
    );
  }
});

React.render(<App />, document.body);

Props

once

Type: Bool Default: false

Once the lazy loaded component is loaded, do not detect scroll/resize event anymore. Useful for images or simple components.

offset

Type: Number Default: 0

Say if you want to preload a module even if it's 100px below the viewport (user have to scroll 100px more to see this module), you can set offset props to 100. On the other hand, if you want to delay loading a module even if it's top edge has already appeared at viewport, set offset props to negative number will make it delay loading.

scroll

Type: Bool Default: true

Respond to scroll event, this is default behaviour.

resize

Type: Bool Default: false

Respond to resize event, set it to true if you do need LazyLoad listen resize event.

NOTICE If you tend to support legacy IE, set this props carefully, refer to this question for further reading.

Props added to children

Like the example above, <MyComponent> will get following extra props:

visible

Type: Bool

Is component currently visible

firstTimeVisible

Is component first time visible, useful for children component's componentWillReceiveProps detect whether or not should query new data.

Scripts

$ npm run demo:watch
$ npm run build

License

MIT