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Here you can Sed posuere consectetur est at lobortis. Donec ullamcorper nulla non metus auctor fringilla. Maecenas sed diam eget risus varius blandit sit amet non magna. Donec id elit non mi porta gravida at eget metus. Praesent commodo cursus magna, vel scelerisque nisl consectetur et.

            
              <div class="burnese-mtn-dogs-container"></div>
            
          
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              $base-color: #f0f0d8;
$background-color: darken($base-color, 5%);
$border-color: #604848;
$filler-color: darken($base-color, 20%);
$text-color: #6f6e5a;

$rhythm: 20px;

// Slidable component-specific styles
.Slidable {
  .slidable-container {
    overflow: hidden;
    position: relative;
  }

  .slidable-content {
    position: absolute;
    width: 100%;

    > * {
      position: relative;
      z-index: 10;
    }
  }

  .previous-children {
    position: absolute;
    top: 0;
    width: 100%;
    z-index: 1;
  }
}


// demo styles
.slidable-demo {
  background: $background-color;
  border: 1px solid #ddd;
  color: $text-color;
  font-family: Helvetica;
  margin: 0 auto;
  max-width: 800px;
  min-height: 200px;
  text-align: center;
  position: relative;
  width: 100%;
  
  header {
    background: $background-color;
    cursor: pointer;
    font-size: 24px;
    font-weight: bold;
    line-height: $rhythm * 2;
    padding: 10px 0;
    
    &:hover {
      background: darken($background-color, 5%);
    }
  }
  
  strong {
    font-weight: bold;
  }
    
  a {
    &, &:visited {
      color: inherit;
      
      &:hover {
        color: darken($text-color, 10%);
      }
    }
  }
  
  h3 {
    font-size: 20px;
    font-weight: bold;
    line-height: $rhythm * 2;
    padding: $rhythm 0 0;
  }
  
  p {
    margin: 20px auto;
    line-height: $rhythm;
    width: 80%;
  }
  
  ul {
    background: $border-color;
    display: flex;
    flex-flow: row wrap;
    width: 100%;
        
    li {
      border: 5px solid $border-color;
      flex: 1 1 25%;
      
      &:nth-child(2n) {
        border-color: lighten($border-color, 20%);
      }
      
      img {
        display: block;
        width: 100%;
      }
    }
  }
  
  .drawer {
    background: $base-color;
  }
  
  .other-things-on-the-page {
    font-size: 0;
    position: relative;
      
    img {
      // this is just a hack for prefetching the image since our list elements in the slidable are auto-height
      display: none;
    }
    
    > div {
      background: $filler-color;
      display: inline-block;
      height: 5px;
      margin: 0;
      padding: 0;
      width: 5px;
    }
  }
}
            
          
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              const IMG_SOURCE = 'https://gfp-nnw0orriao.netdna-ssl.com/wp-content/uploads/2016/07/Bernese-Mountain-Dog-600x600.jpg';

class Slidable extends React.Component {
  constructor(props) {
    super();
    
    this.state = {
      /** {number} - The pixel height of the container. Or `null` to set the height to auto. */
      height: null,
      /**
       * {React.Children} - We now cycle through two children, children0 and children1, and
       * update the classname of their container based on which one is currently the previous
       * children. Initially, children0 is current and children1 is previous, which is null.
       * After the transition, we set our previous children position to null.
       */
      children0: props.children,
      children1: null,
      /** {number} - reference to the which children set are the previous children */
      previousChildrenPosition: 1,
      /**
        * {number} - The previous pixel height of the container, used to determine when to update.
        *    To minimize forced layouts, we saved the current height as the previous height after
        *    that height's animation.
        */
      prevHeight: 0,
      /** {boolean} - Whether or not the component is in the process of changing height. */
      transitioning: false
    };
  }

  componentWillReceiveProps(nextProps) {
    var newChildrenNumber = (this._arePreviousChildrenPositionOne()) ? 1 : 0,
        newPreviousChildrenPosition = (this._arePreviousChildrenPositionOne()) ? 0 : 1;

    if (this.props.updateTriggerCondition !== nextProps.updateTriggerCondition) {
      // if previous children is currently child number 2, replace it with new children
      // which would be `this.props` after update
      this.setState({
        [`children${newChildrenNumber}`]: nextProps.children,
        previousChildrenPosition: newPreviousChildrenPosition,
        prevHeight: ReactDOM.findDOMNode(this.refs.content).offsetHeight,
        transitioning: false
      });
    } else {
      // we have to update children props every time
      this.setState({
        [`children${newPreviousChildrenPosition}`]: nextProps.children
      });
    }
  }

  componentDidUpdate(prevProps) {
    var contentHeight;

    if (this.props.updateTriggerCondition !== prevProps.updateTriggerCondition) {
      window.requestAnimationFrame(() => {
        contentHeight = ReactDOM.findDOMNode(this.refs.content).offsetHeight;

        // first step in new animation: set height from 'auto' back to a number
        // so that we have a starting height.
        if (contentHeight !== this.state.prevHeight && !this.state.transitioning) {
          this.setState({
            height: this.state.prevHeight,
            transitioning: true
          }, () => {
            // we adjust height from old height (ie 0) to new height in next frame so that
            // the browser doesn't batch style changes--otherwise the animation wouldn't trigger
            window.requestAnimationFrame(() => {
              // use setTimeout because transitionend events fire inconsistently across browsers 🙁
              window.setTimeout(this.onTransitionEnd.bind(this), this.props.transitionDuration);
              this.setState({height: contentHeight})    
            });
          });
        }
      });
    }
  }

  /**
   * Called when the height transition ends on the container. It removes the
   * content from the DOM when the container is done sliding out, and sets
   * the height to 'auto' after the container is done sliding in.
   */
  onTransitionEnd() {
    var childrenNumberToRemove = (this._arePreviousChildrenPositionOne()) ? 1 : 0;

    this.setState({
      [`children${childrenNumberToRemove}`]: null,
      height: null
    });
  }

  _arePreviousChildrenPositionOne() {
    return this.state.previousChildrenPosition === 1;
  }
  
  render() {
    var contentStyle = {
          position: (this.state.height === null) ? 'relative' : 'absolute'
        },
        containerStyle = {
          height: (this.state.height === null) ? 'auto' : this.state.height,
          transition: `height ${this.props.transitionDuration}ms`
        };

    return (
      <div className='Slidable'>
        <div ref='container' style={containerStyle} className='slidable-container'>
          <div ref='content' style={contentStyle} className='slidable-content'>
            {/* treat each child set identically and only edit the classname for each */}
            <div className={!this._arePreviousChildrenPositionOne() ? 'previous-children' : ''}>
              {this.state.children0}
            </div>
            <div className={this._arePreviousChildrenPositionOne() ? 'previous-children' : ''}>
              {this.state.children1}
            </div>
          </div>
        </div>
      </div>
    );
  }
}


class SlidableDemo extends React.Component {
  constructor() {
    super();
    
    this.state = {drawerOpen: false};
  }
 
  onHeaderClick() {
    this.setState({drawerOpen: !this.state.drawerOpen});
  }
  
  render() {
    return (
      <div className='slidable-demo'>
        <header onClick={this.onHeaderClick.bind(this)}>
          <h1>Toggle me for a surprise!</h1>
        </header>
        <Slidable
          transitionDuration={400}
          updateTriggerCondition={this.state.drawerOpen}
        >
          {this.state.drawerOpen ? (
            <div className='drawer'>
              <h3>...it's PUPPIEEEEES!!!</h3>
              <p>
                We've added a bunch of dummy elements in the <strong>.other-things-on-the-page</strong> element below to mimic the real-world effects of doing a lot of work per frame.
              </p>
              <p>
                Here we are animating the <strong>height</strong> property, and we definitely aren't hitting 60fps :(. We know we can avoid layouts and paints when animating transforms, but how do we do that when opening a drawer of unknown height?
              </p>
              <ul>
                <li><img src={IMG_SOURCE} /></li>                
                <li><img src={IMG_SOURCE} /></li>                
                <li><img src={IMG_SOURCE} /></li>                
              </ul>
            </div>
          ) : null}
        </Slidable>
        <section className='other-things-on-the-page'>
          <img src={IMG_SOURCE} />
          {Array.apply(null, new Array(25000)).map(() => <div />)}
        </section>
      </div>
    )
  }
}

ReactDOM.render(<SlidableDemo />, document.querySelector('.burnese-mtn-dogs-container'));
            
          
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