title: Uncaught ReferenceError: mountNode is not defined
body: <p>forgive me i've searched everywhere and I'm new in reactjs and trying out examples. I have an error</p>
  
  <pre><code>Uncaught ReferenceError: mountNode is not defined 
  </code></pre>
  
  <p>I am following the example from here <a href="http://facebook.github.io/react/tips/initial-ajax.html">http://facebook.github.io/react/tips/initial-ajax.html</a></p>
  
  <p>and my code looks like this</p>
  
  <pre><code>&lt;!DOCTYPE html&gt;
  &lt;html&gt;
    &lt;head&gt;
      &lt;title&gt;&lt;%= title %&gt;&lt;/title&gt;
      &lt;link rel='stylesheet' href='/stylesheets/style.css' /&gt;
      &lt;script src="//code.jquery.com/jquery-1.11.0.min.js"&gt;&lt;/script&gt;
      &lt;script src="/javascripts/reactjs/react.js"&gt;&lt;/script&gt;
      &lt;script src="/javascripts/reactjs/JSXTransformer.js"&gt;&lt;/script&gt;
    &lt;/head&gt;
    &lt;body&gt;
      &lt;h1&gt;&lt;%= title %&gt;&lt;/h1&gt;
      &lt;p&gt;Welcome to &lt;%= title %&gt;&lt;/p&gt;
      &lt;div id="example"&gt;&lt;/div&gt;
      &lt;script src="/javascripts/reactjs/build/helloworld.js"&gt;&lt;/script&gt;
      &lt;script type="text/jsx"&gt;
      /** @jsx React.DOM */
  
      var UserGist = React.createClass({
        getInitialState: function() {
          return {
            username: '',
            lastGistUrl: ''
          };
        },
  
        componentDidMount: function() {
          $.get(this.props.source, function(result) {
            var lastGist = result[0];
            this.setState({
              username: lastGist.owner.login,
              lastGistUrl: lastGist.html_url
            });
          }.bind(this));
        },
  
        render: function() {
          return (
            &lt;div&gt;
              {this.state.username}last gist is
              &lt;a href={this.state.lastGistUrl}&gt;here&lt;/a&gt;.
            &lt;/div&gt;
          );
        }
      });
  
      React.renderComponent( &lt;UserGist source="https://api.github.com/users/octocat/gists" /&gt;, mountNode );
  
  
      &lt;/script&gt;
  
    &lt;/body&gt;
  &lt;/html&gt;
  </code></pre>
  
  <p>Thank you in advance!</p>