

<!-- Original:  Ronnie T. Moore, Editor -->
<!-- Web Site:  The JavaScript Source -->
<!-- This script and many more are available free online at -->
<!-- The JavaScript Source!! http://javascript.internet.com -->


<!-- Begin

function isValidDate(dateStr) {
// Date validation function courtesty of 
// Sandeep V. Tamhankar (stamhankar@hotmail.com) -->
// Checks for the following valid date formats:
// MM/DD/YY   MM/DD/YYYY   MM-DD-YY   MM-DD-YYYY

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("Date is not in a valid format.")
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("Month "+month+" doesn't have 31 days!")
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("February " + year + " doesn't have " + day + " days!");
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 (month + "/" + day + "/" + 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

//	Set up values from the drop down
var menstrualMonth = pregform.menstrualMonth.value;
var menstrualDay = pregform.menstrualDay.value;
var menstrualYear = pregform.menstrualYear.value

//	make sure that february date is set to 28 or lower
if(menstrualMonth == 2 && menstrualDay > 28) {
	menstrualDay = 28;
}

//	make sure that april, june, sept, and nov date is set to 30 if 31 is selected
if((menstrualMonth == 4 || menstrualMonth == 6 || menstrualMonth == 9 || menstrualMonth == 11) && menstrualDay == 31) {
	menstrualDay = 30;
}

//	build the date string
var menstrualDate = menstrualMonth + "/" + menstrualDay + "/" + menstrualYear;

//	populate hidden field.
pregform.menstrual.value = menstrualDate;

if (isValidDate(pregform.menstrual.value)) { // Validates menstual date 
menstrualinput = new Date(pregform.menstrual.value);
menstrual.setTime(menstrualinput.getTime())

}

else return false; // otherwise exits

 
cycle = (pregform.cycle.value == "" ? 28 : pregform.cycle.value); // defaults to 28

// validates cycle range, from 22 to 45
if (pregform.cycle.value != "" && (pregform.cycle.value < 22 || pregform.cycle.value > 45)) {
alert("Your cycle length is either too short or too long for \n"
+ "calculations to be very accurate!  We will still try to \n"
+ "complete the calculation with the figure you entered. ");

}

luteal = (pregform.luteal.value == "" ? 14 : pregform.luteal.value); // defaults to 14
// validates luteal range, from 9 to 16
if (pregform.luteal.value != "" && (pregform.luteal.value < 9 || pregform.luteal.value > 16)) {
alert("Your luteal phase length is either too short or too long for \n"
+ "calculations to be very accurate!  We will still try to complete \n"
+ "the calculation with the figure you entered. ");

}

 
// 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 = dispDate(duedate);

// 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 = weeks + " week" + (weeks == 0 || weeks > 1 ? "s" : "") + ", " + days + " day" + (days == 0 || days > 1 ? "s" : "");

if (weeks < 0 && days < 0) {
fetalage = "LMP is future date";
}

pregform.fetalage.value = fetalage;

//	This block of code redirects according to how many weeks are calculated
if (weeks <2) {
window.location.href = "http://baby2see.com/development/not_pregnant.html?menstrual=" + menstrualDate + "&cycle=" + cycle;
}
if (weeks > 1 && weeks < 13) {
window.location.href = "http://baby2see.com/development/trimester_1.html?menstrual=" + menstrualDate + "&cycle=" + cycle;
} 
if (weeks > 12 && weeks < 27) {
window.location.href = "http://baby2see.com/development/trimester_2.html?menstrual=" + menstrualDate + "&cycle=" + cycle;
}
if (weeks > 26 && weeks < 41){
window.location.href = "http://baby2see.com/development/trimester_3.html?menstrual=" + menstrualDate + "&cycle=" + cycle;
}
if (weeks > 40){
window.location.href = "http://baby2see.com/development/postdue.html?menstrual=" + menstrualDate + "&cycle=" + cycle;
}


return false; // form should never submit, returns false
}
//  End -- >