title: how to 'offset' a date/time using moment
body: <p>I have an input box with a date (user selected).  I want to use moment.js to offset the date selected by a timezone, for example 'Europe/London'.  So lets' say my date is (2/24/2017), how do I get moment to give me the date as:</p>
  
  <p>current date time is 2/24/2017 4:18:00</p>
  
  <p>So I want it to return 2/25/2017 12:18:00 which would be the current time in London England? </p>
  
  <pre><code>var x = moment().tz(dateStart, 'London/Europe').format();
  </code></pre>
  
  <p>but it just keeps giving me the date time now.</p>
  
  <p>Thanks.</p>