momentjs

<!DOCTYPE html>
<html>

  <head>
    <script data-require="moment.js@2.10.2" data-semver="2.10.2" src="https://cdnjs.cloudflare.com/ajax/libs/moment.js/2.10.2/moment.min.js"></script>
    <link rel="stylesheet" href="style.css" />
    <script src="script.js"></script>
  </head>

  <body>
    <h1>Hello Plunker!</h1>
  </body>

</html>

// Code goes here

var date = new Date();
var week = moment(date).format('dddd');
alert(week);

/* Styles go here */