title: Getting the difference between 2 dates in Javascript in hours, minutes, seconds with UTC
body: <p>Like the title says, I need to get the difference between two dates and display the hours, minutes, seconds that counts down to the finish date. I have this:</p>
  
  <p><div class="snippet" data-lang="js" data-hide="false" data-console="true" data-babel="false">
  <div class="snippet-code">
  <pre class="snippet-code-js lang-js prettyprint-override"><code>function timer(){
   
   'use strict'
   
   var date1 = new Date().getTime();
   var date2 = new Date("05/29/2017").getTime();
   
   var diff = date2 - date1;
   
   var seconds = diff / 1000;
   var minutes = (diff / 1000) / 60;
   var hours = minutes / 60;
  
   var message = 'Hours: ' + Math.floor(hours) + " Minutes: " + Math.floor(minutes) + " Seconds: " + Math.floor(seconds); 
   
   var output = document.getElementById('output');
   if (output.textContent !== undefined) {
    output.textContent = message;
   } else {
    output.innerText = message;
   }
  }
  setInterval("timer()", 1000);
  window.onload = timer;</code></pre>
  <pre class="snippet-code-html lang-html prettyprint-override"><code>&lt;!doctype html&gt;
  &lt;html lang="en"&gt;
  &lt;head&gt;
      &lt;meta charset="utf-8"&gt;
      &lt;title&gt;hi&lt;/title&gt;
      &lt;!--[if lt IE 9]&gt;
      &lt;script src="http://html5shiv.googlecode.com/svn/trunk/html5.js"&gt;&lt;/script&gt;
      &lt;![endif]--&gt;
      &lt;link rel="stylesheet" href="css/form.css"&gt;
  &lt;/head&gt;
  &lt;body&gt;
      &lt;!-- auction.html --&gt;
      &lt;form action="#" method="post" id="theForm"&gt;
          &lt;fieldset&gt;&lt;legend&gt;Auction ends on May 29, 2017&lt;/legend&gt;
        &lt;p&gt;Refresh page for updated times.&lt;/p&gt;
     &lt;div id="output"&gt;&lt;/div&gt;
              &lt;input type="submit" value="Refresh" id="submit"&gt;
          &lt;/fieldset&gt;
      &lt;/form&gt;
      &lt;script src="js/auction.js"&gt;&lt;/script&gt;
  &lt;/body&gt;
  &lt;/html&gt;</code></pre>
  </div>
  </div>
  </p>
  
  <p>The instructions for my assignment state that I need to: "Choose an end date in the future (several weeks after assignment is due) and use UTC.  Display the hours, minutes, and seconds left until the auction ends."
  I'm kind of lost on how to implement the UTC and create a proper countdown? I'm not even sure if I did any of it right (I am just starting to learn j.s). How should I fix my code?</p>