title: What is the instanceof operator in JavaScript?
body: <p>The <code>instanceof</code> keyword in JavaScript can be quite confusing when it is first encountered, as people tend to think that JavaScript is not an object-oriented programming language.</p>
  
  <ul>
  <li>What is it?</li>
  <li>What problems does it solve?</li>
  <li>When is it appropriate and when not?</li>
  </ul>