title: Get week of quarter using Date object
body: <p>How to get the <strong>week of quarter</strong> using <code>new Date()</code>?</p>
  
  <p>For example 9/27/2019, we're in Q3 and last week of month so therefore <code>weekOfQuarter = 13</code>.</p>
  
  <p>Assume ISO8601 format of week: Monday through Sunday.</p>