title: How to ignore user's time zone and force Date() use specific time zone
body: <p>In an JS app, I receive timestamp (eq. <code>1270544790922</code>) from server (Ajax).</p>
  
  <p>Basing on that timestamp I create <code>Date</code> object using:</p>
  
  <pre><code>var _date = new Date();
  _date.setTime(1270544790922);
  </code></pre>
  
  <p>Now, <code>_date</code> decoded timestamp in current user locale time zone. I don't want that.</p>
  
  <p>I would like _<code>date</code> to convert this timestamp to current time in city of Helsinki in Europe (disregarding current time zone of the user). </p>
  
  <p>How can I do that?</p>