Toon weeknummer
<!doctype html>
<html>
<head>
<meta charset="utf-8">
<title>Toon weenummer</title>
<script src="https://code.jquery.com/jquery-3.3.1.js"></script>
</head>
<body>
<div id="weeknummer"></div>
<script>
Date.prototype.getWeek = function() {
var dF = new Date(this.getFullYear(),0,1);
var dT = new Date(this.getFullYear(),this.getMonth(),this.getDate());
var dY = ((dT - dF +1)/86400000);
return Math.ceil(dY/7)
};
jQuery(function(){
var dT = new Date();
var wN = dT.getWeek();
$("#weeknummer").html(wN);
});
</script>
</body>
</html>