title: jQuery error in .js file
body: <p>I've just completed the JavaScript and jQuery basics, and I got two errors while executing the jquery in the .js file</p>
  
  <ol>
  <li><code>$</code> is uses before was defined </li>
  <li>Missing 'used strict' statement</li>
  </ol>
  
  <p>What should I do?</p>