//Omzetten dagstring
function dagveld(dayObj) {
// Get date strings
var dayInteger, dayString, 
dayInteger=dayObj.selectedIndex
dayString=dayObj.options[dayInteger].value
// Display property values
document.bcalc.dayeen.value=dayString
}
//Omzetten maandstring
function maandveld(monthObj) {
// Get date strings
var monthInteger, monthString, 
monthInteger=monthObj.selectedIndex
monthString=monthObj.options[monthInteger].value
// Display property values
document.bcalc.maandeen.value=monthString
}
//Omzetten jaarstring
function jaarveld(yearObj) {
// Get date strings
var yearInteger, yearString, 
yearInteger=yearObj.selectedIndex
yearString=yearObj.options[yearInteger].value
// Display property values
document.bcalc.jaareen.value=yearString
}
function totaal()
{
veld=document.bcalc
veld.menstrual.value=veld.maandeen.value+"/"+veld.dayeen.value+"/"+veld.jaareen.value
}

function isValidDate(dateStr) {
 
var datePat = /^(\d{1,2})(\/|-)(\d{1,2})\2(\d{4})$/; // requires 4 digit year
 
var matchArray = dateStr.match(datePat); // is the format ok?
if (matchArray == null) {
alert("U moet eerst de dag daarna de maand en dan het jaar ingeven.")
return false;
}
month = matchArray[1]; // parse date into variables
day = matchArray[3];
year = matchArray[4];
if (month < 1 || month > 12) { // check month range
alert("Month must be between 1 and 12.");
return false;
}
if (day < 1 || day > 31) {
alert("Day must be between 1 and 31.");
return false;
}
if ((month==4 || month==6 || month==9 || month==11) && day==31) {
alert("Maand "+month+" heeft geen 31 dagen!")
return false;
}
if (month == 2) { // check for february 29th
var isleap = (year % 4 == 0 && (year % 100 != 0 || year % 400 == 0));
if (day>29 || (day==29 && !isleap)) {
alert("Februari " + year + " heeft geen " + day + " dagen!");
return false;
   }
}
return true;
}
 
function dispDate(dateObj) {
month = dateObj.getMonth()+1;
month = (month < 10) ? "0" + month : month;
 
day   = dateObj.getDate();
day = (day < 10) ? "0" + day : day;
 
year  = dateObj.getYear();
if (year < 2000) year += 1900;
 
return (day + "/" + month + "/" + year);
}
 
function pregnancyCalc(pregform) {
menstrual = new Date(); // creates new date objects
ovulation = new Date();
duedate = new Date();
today = new Date();
cycle = 0, luteal = 0; // sets variables to invalid state ==> 0
 
if (isValidDate(pregform.menstrual.value)) { // Validates menstual date 
menstrualinput = new Date(pregform.menstrual.value);
menstrual.setTime(menstrualinput.getTime())
}
else return false; // otherwise exits
 
//vaste waarden gemaakt
cycle=28;
luteal = 14;
 
 
// sets ovulation date to menstrual date + cycle days - luteal days
// the '*86400000' is necessary because date objects track time
// in milliseconds;  86400000 milliseconds equals one day
ovulation.setTime(menstrual.getTime() + (cycle*86400000) - (luteal*86400000));
pregform.conception.value = dispDate(ovulation);
 
// sets due date to ovulation date plus 266 days
duedate.setTime(ovulation.getTime() + 266*86400000);
pregform.duedate.value = "Je bent op " + dispDate(duedate) + " uitgerekend";
 
// sets fetal age to 14 + 266 (pregnancy time) - time left
var fetalage = 14 + 266 - ((duedate - today) / 86400000);
weeks = parseInt(fetalage / 7); // sets weeks to whole number of weeks
days = Math.floor(fetalage % 7); // sets days to the whole number remainder
 
// fetal age message, automatically includes 's' on week and day if necessary
fetalage = "Je bent nu " + weeks + " we" + (weeks > 1 ? "ken" : "ek") + ", " + days + " dag" + (days > 1 ? "en" : "") + " zwanger";
pregform.fetalage.value = fetalage;
 
return false; // form should never submit, returns false
}

 
function MM_callJS(jsStr) { //v2.0
  return eval(jsStr)
}