Moment JS
Example of parsing and formatting a Date with Moment JS.
by asha_vyshakh
HTML
<script src="http://momentjs.com/downloads/moment.js"></script>
JavaScript
function getWeekNumber(thisDate) {
var dt = new Date(thisDate);
var thisDay = dt.getDate();
var newDate = dt;
newDate.setDate(1); // first day of month
var digit = newDate.getDay();
var Q = (thisDay + digit) / 7;
var R = (thisDay + digit) % 7;
if (R !== 0) window.alert(Math.ceil(Q)) ;
else window.alert(Q); }
getWeekNumber("08/22/2018");