title: Can you use constant variables in JavaScript?
body: <p>I read on one site that you can make <em>constant</em> variables in JavaScript like:</p>
  
  <pre><code>const x = 20;
  </code></pre>
  
  <p>but on another site I read that you can't. So I am confused now what is it now?</p>
  
  <p>Also in Visual Studio 2010 when I write <code>const</code> it underlines it in the JavaScript file and shows syntax error.</p>