// JavaScript Document

function trimAll(sString) {
	while (sString.substring(0,1) == ' '){
		sString = sString.substring(1, sString.length);
	};
	while (sString.substring(sString.length-1, sString.length) == ' '){
		sString = sString.substring(0,sString.length-1);
	};
	return sString;
};

function check_date(strDate){
	var checkstr = "0123456789";
	//var DateField = field;
	var DateValue = strDate;
	var DateTemp = "";
	var seperator = ".";
	var day;
	var month;
	var year;
	var leap = 0;
	var err = 0;
	var i;

	err = 0;
	//DateValue = DateField.value;
	/* Delete all chars except 0..9 */
	for (i = 0; i < DateValue.length; i++) {
	  if (checkstr.indexOf(DateValue.substr(i,1)) >= 0) {
		 DateTemp = DateTemp + DateValue.substr(i,1);
	  }
	}
	DateValue = DateTemp;
	/* Always change date to 8 digits - string*/
	/* if year is entered as 2-digit / always assume 20xx */
	if (DateValue.length == 6) {
	  DateValue = DateValue.substr(0,4) + '20' + DateValue.substr(4,2); }
	if (DateValue.length != 8) {
	  err = 19;}
	/* year is wrong if year = 0000 */
	year = DateValue.substr(4,4);
	if (year == 0) {
	  err = 20;
	}
	/* Validation of month*/
	month = DateValue.substr(0,2);
	if ((month < 1) || (month > 12)) {
	  err = 21;
	}
	/* Validation of day*/
	day = DateValue.substr(2,2);
	if (day < 1) {
	 err = 22;
	}
	/* Validation leap-year / february / day */
	if ((year % 4 == 0) || (year % 100 == 0) || (year % 400 == 0)) {
	  leap = 1;
	}
	if ((month == 2) && (leap == 1) && (day > 29)) {
	  err = 23;
	}
	if ((month == 2) && (leap != 1) && (day > 28)) {
	  err = 24;
	}
	/* Validation of other months */
	if ((day > 31) && ((month == "01") || (month == "03") || (month == "05") || (month == "07") || (month == "08") || (month == "10") || (month == "12"))) {
	  err = 25;
	}
	if ((day > 30) && ((month == "04") || (month == "06") || (month == "09") || (month == "11"))) {
	  err = 26;
	}
	
	/* if 00 ist entered, no error, deleting the entry */
	/*if ((day == 0) && (month == 0) && (year == 00)) {
	  err = 0; day = ""; month = ""; year = ""; seperator = "";
	}*/
	
	if(trimAll(DateValue) == ''){
		err = 30;
	};

	/* if no error, write the completed date to Input-Field (e.g. 13.12.2001) */
	if (err == 0) {
	  //DateField.value = day + seperator + month + seperator + year;
	  return true;
	}
	/* Error-message if err != 0 */
	else {
	  //alert("Date is incorrect!");
	  //DateField.select();
	  //DateField.focus();
	  
	  return false;
	}
}