onload = function() {
	var e, i = 0;
	while (e = document.getElementById('beschikbaarheid').getElementsByTagName ('DIV') [i++]) {
		if (e.className == 'on' || e.className == 'off') {
		e.onclick = function () {
			var getEls = document.getElementsByTagName('DIV');
				for (var z=0; z<getEls.length; z++) {
				getEls[z].className=getEls[z].className.replace('show', 'hide');
				getEls[z].className=getEls[z].className.replace('on', 'off');
				}
			this.className = 'on';
			var max = this.getAttribute('title');
			document.getElementById(max).className = "show";
			}
		}
	}
}
function getWeken(str,str2,str3)
{

var datumVanArray = str.split("-");
var datumMaxArray = str2.split("-");

var day1 = datumVanArray[0];
var day2 = datumMaxArray[0];
var month1 = datumVanArray[1];
var month2 = datumMaxArray[1];
var year1 = datumVanArray[2];
var year2 = datumMaxArray[2];

var datvan=new Date(year1, month1 - 1 , day1) //Month is 0-11 in JavaScript
var dattot=new Date(year2, month2 - 1 , day2) //Month is 0-11 in JavaScript

var one_day=1000*60*60*24

var dif = Math.round((dattot.getTime()-datvan.getTime())/(one_day));
var weken = Math.round(dif/7);
var i=1;
var code = '<select name="weken" id="weken">';

if (weken >= 4) weken = 4; // max aantal te reserveren weken
while (i <= weken)
{
code = code + '<option value="' + i + '">' + i + '</option>'

i=i+1;
}

code = code + "</select>";
document.getElementById(str3).innerHTML=code;

}