title: Error: ‘$’ is not defined.[no-undef]
body: <p>I wanna use some jQuery to make a <strong>sticky nav bar</strong> but I get the errors </p>
  
  <blockquote>
    <p><code>ERROR: ‘$’ is not defined. [no-undef].</code><br>
    <code>ERROR: ‘document ’ is not defined. [no-undef]</code></p>
  </blockquote>
  
  <p>and the code doesn’t work. Can anybody help me why I get these errors and how to solve it?</p>