title: VS Code - ReferenceError: $ is not defined WHY?
body: <p>I am working on udacity design patters course. There are giving materials and I have implemented some onto it then tried to debugging. However it gives me the error saying I have no linked to jQuery even though it had been defined as  </p>
  
  <pre><code>&lt;script src="http://ajax.googleapis.com/ajax/libs/jquery/1.11.1/jquery.min.js"&gt;&lt;/script&gt;
  &lt;script src="js/retain.js"&gt;&lt;/script&gt;
  </code></pre>
  
  <p>on separate index.html file</p>
  
  <p>Because the files were provided by the course, it should be written correctly. So I must do something beforehand...</p>
  
  <p>I am new to JS code, searched &amp; going through many videos but still have no ideas: (I have set config.json (as asked on introduction video <a href="https://www.youtube.com/watch?v=6cOsxaNC06c&amp;t=103s" rel="nofollow noreferrer">https://www.youtube.com/watch?v=6cOsxaNC06c&amp;t=103s</a>). I would be appreciated if anyone can help in anyway! (or anyone can direct me to good tutorials of debugging on VS Code ). Thank you in advance. </p>