title: How to get duration in weeks with Moment.js?
body: <p>I use <code>moment.js</code> to format durations in human readable format.<br>
  For example (<code>d</code> is a <code>Date</code> object):</p>
  
  <pre>moment(d).subtract("days", 3).from(d)  // returns "3 days ago"</pre>
  
  <p>Now I would like to get "2 weeks ago" but the code below returns the durations in days</p>
  
  <pre>moment(d).subtract("weeks", 2).from(d) // returns "14 days ago" i/o "2 weeks ago"</pre>
  
  <p>How can I get "2 weeks ago" with <code>moment.js</code>?</p>