title: Node.js "res is not defined"
body: <p>What Javascript do I add to define res?  Thanks!</p>
  
  <p>Error message:</p>
  
  <blockquote>
    <p>ReferenceError: res is not defined</p>
  </blockquote>
  
  <p>Code:</p>
  
  <pre><code>app.get('/', function(request, response) {
      res.sendFile(path.join(__dirname, '/public', 'index.html'));
  })
  </code></pre>