title: Calculate working days with JavaScript taking into account holidays
body: <p>How can I adapt the code in thus question to take into account national holidays.</p>
  
  <p><a href="https://stackoverflow.com/questions/7952239/getting-working-days-using-javascript">Getting Working Days Using Javascript</a></p>
  
  <p>I know I will need an array of dates which are holidays but what needs to be added into the logic ?</p>