title: How to know whether a country is using Daylight Saving Time using JavaScript?
body: <p>I'm in China and I've a friend who is in other countries. e.g. UK, USA, New Zealand...</p>
  
  <p>I know his country's name in English and  time zone there.</p>
  
  <p>But how can I know whether his country is using DST now or not? Any ideas?</p>
  
  <p>Thank you!</p>