title: Get timezone offset from timezone name using Javascript
body: <p>I found many solution that gives Timezone name from offset value. But I have Timezone name and I want offset value for that. I tried setTimezone('Asia/Kolkata'), but I think their is no method like setTimezone.</p>
  
  <p>example:</p>
  
  <pre><code>Asia/Kolkata should give me -330 ( offset )
  </code></pre>