Animate

"React allows us to animate objects easily with its react-addons-css-transition-group add-on."

"This gives us a handle to the ReactCSSTransitionGroup object, which is what we will be using to animate changes in data, such as addition of cats, faving/unfaving, and so on."

"Let's start by animating the addition of new cats to the stream, shall we?"

render() {
    let Cats = this.state.catGenerator.Cats;

    return (
        <div>
          <div>
            <ReactCSSTransitionGroup transitionName="cats" 
                                     transitionEnterTimeout={500} 
                                     transitionLeaveTimeout={300}
                                     transitionAppear={true} 
                                     transitionAppearTimeout={500}>
              {Cats.map(cat => (
                  <div key={cat.cid} style={{float: 'left'}}>
                    <Link to={`/pictures/${cat...