Edit in JSFiddle

var ReactiveUpdatesComponent = React.createClass({
  render: function() {
    return ( < p > Type in the input box: < input type = "text" > < /input>{this.props.date.toTimeString()}</p > );
  }
})
setInterval(function() {
  ReactDOM.render( < ReactiveUpdatesComponent date = {
      new Date()
    }
    />,
    document.getElementById('container')
  );
}, 1000);
<script src="https://facebook.github.io/react/js/jsfiddle-integration-babel.js"></script>

<div id="container">
  <!-- This element's contents will be replaced with your component. -->
</div>