title: using moment.js to set initial time zone
body: <p>I try to follow <strong>moment.js</strong> to init specify <code>eastern 8</code> time zone.</p>
  
  <p>I change my os time zone to <code>western 4</code>, then I input the same timestamp as below.</p>
  
  <pre><code>moment().utcOffset(-240);
  moment(1473998400000).toDate();
  
  moment().utcOffset(480);
  moment(1473998400000).toDate();
  
  // both output &gt;&gt;&gt; Fri Sep 16 2016 00:00:00 GMT-0400 (EDT) 
  </code></pre>
  
  <p>but I can't understand that why I also get the same output from different initial timezone?</p>
  
  <p>what I did wrong :(</p>