React.Children.count

Example of React.Children.count for "Introduction to React"

HTML

<script src="https://cdnjs.cloudflare.com/ajax/libs/react/0.13.1/JSXTransformer.js"></script>
<script src="https://cdnjs.cloudflare.com/ajax/libs/react/0.13.1/react-with-addons.js"></script>
<script src="https://facebook.github.io/react/js/jsfiddle-integration.js"></script>

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

JavaScript 1.7

var MyComponent = React.createClass({
  render: function() {
          var cnt = React.Children.count(this.props.children);
          console.log(cnt);
    return (
      <div>
        {this.props.name}
      </div>
    );
  }
});

React.render(<MyComponent name="frodo" />, document.getElementById('container'));