title: How to addition seconds with seconds in JavaScript?
body: <p>I have my current time in seconds and duration time in seconds.
  I want to add both seconds to calculate the end time of the song (for example).
  But i have a weird format in the result.</p>
  
  <p>Here is my code :</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>// This is my song's duration
  var duration = new Date("Sept 21, 2019 00:03:32");
  var durationSeconds = duration.getSeconds();
  
  // Current second
  var date = new Date();
  var seconds = date.getSeconds();
  var differenceSecondsConverted = date.setSeconds(seconds + durationSeconds);
  
  console.log(differenceSecondsConverted);</code></pre>
  </div>
  </div>
  </p>
  
  <p>And the result is something like : 1569102592740</p>
  
  <p>Thanks</p>