demo10/index.html

<!DOCTYPE html>
<html>
  <head>
    <meta charset="UTF-8" />
    <script src="../build/react.development.js"></script>
    <script src="../build/react-dom.development.js"></script>
    <script src="../build/babel.min.js"></script>
  </head>
  <body>
    <div id="example"></div>
    <script type="text/babel">
      class Hello extends React.Component {
        constructor(props) {
          super(props)
          this.state = {
            opacity: 1.0
          };
        }

        componentDidMount() {
          this.timer = setInterval(function () {
            var opacity = this.state.opacity;
            opacity -= .05;
            if (opacity < 0.1) {
              opacity = 1.0;
            }
            this.setState({
              opacity: opacity
            });
          }.bind(this), 100);
        }

        render() {
          return (
            <div style={{opacity: this.state.opacity}}>
              Hello {this.props.name}
            </div>
          );
        }
      }
        
      ReactDOM.render(
        <Hello name="world"/>,
        document.getElementById('example')
      );
    </script>
  </body>
</html>