title: Converting Central Time date to ISO string in current timezone
body: <p>I have a date I know is stored in Central Time. It has the following format: <code>2017-11-19T23:39:35.280000</code>. I want to turn this into an ISO-formatted date in the current timezone. I got it to work when simply creating a <code>new Date()</code> -- but then when I subsequently call <code>.toISOString()</code>, it goes haywire. Here's the code:</p>
  
  <pre><code>function convertCentralToLocal() {
    const centralOffset = 360;
    const dateInCentralMs = new Date('2017-11-19T23:39:35.280000').getTime();
    const now = new Date();
    const localOffset = now.getTimezoneOffset();
  
    // this works: Sun Nov 19 2017 23:39:35 GMT-0600 (CST)
    const d = new Date(dateInCentralMs + ((centralOffset - localOffset) * 60000));
  
    // this seems to give the date six hours off: 2017-11-20T05:39:35.280Z
    const iso = d.toISOString();
  }
  </code></pre>
  
  <p>Is it an issue with GMT? I'm feeling lost.</p>