function checkDate(checkDateField,errorMessage) {
	checkDateField.value = FormatDate(checkDateField.value);
	if (isDate(checkDateField.value)) {
		return true;
	} else {
		alert (errorMessage);
		checkDateField.focus()
	}
}

function isDate(DateToCheck){
	if(DateToCheck==""){return true;}
	var m_strDate = FormatDate(DateToCheck);
	if(m_strDate==""){
	return false;
	}
	var m_arrDate = m_strDate.split("/");
	var m_MONTH = m_arrDate[0];
	var m_DAY = m_arrDate[1];
	var m_YEAR = m_arrDate[2];
	if(m_YEAR.length > 4){return false;}
	m_strDate = m_MONTH + "/" + m_DAY + "/" + m_YEAR;
	var testDate=new Date(m_strDate);
	if(testDate.getMonth()+1==m_MONTH){
	return true;
	} 
	else{
	return false;
	}
	}//end function
	
	
	
	
	function FormatDate(DateToFormat,FormatAs){
	if(DateToFormat==""){return"";}
	if(!FormatAs){FormatAs="mm/dd/yyyy";}
	
	var strReturnDate;
	FormatAs = FormatAs.toLowerCase();
	DateToFormat = DateToFormat.toLowerCase();
	var arrDate
	var arrMonths = new Array("January","February","March","April","May","June","July","August","September","October","November","December");
	var strMONTH;
	var Separator;
	
	while(DateToFormat.indexOf("st")>-1){
	DateToFormat = DateToFormat.replace("st","");
	}
	
	while(DateToFormat.indexOf("nd")>-1){
	DateToFormat = DateToFormat.replace("nd","");
	}
	
	while(DateToFormat.indexOf("rd")>-1){
	DateToFormat = DateToFormat.replace("rd","");
	}
	
	while(DateToFormat.indexOf("th")>-1){
	DateToFormat = DateToFormat.replace("th","");
	}
	
	if(DateToFormat.indexOf(".")>-1){
	Separator = ".";
	}
	
	if(DateToFormat.indexOf("-")>-1){
	Separator = "-";
	}
	
	
	if(DateToFormat.indexOf("/")>-1){
	Separator = "/";
	}
	
	if(DateToFormat.indexOf(" ")>-1){
	Separator = " ";
	}
	
	arrDate = DateToFormat.split(Separator);
	DateToFormat = "";
		for(var iSD = 0;iSD < arrDate.length;iSD++){
			if(arrDate[iSD]!=""){
			DateToFormat += arrDate[iSD] + Separator;
			}
		}
	DateToFormat = DateToFormat.substring(0,DateToFormat.length-1);
	arrDate = DateToFormat.split(Separator);
	
	if(arrDate.length < 3){
	return "";
	}
	
	var MONTH = arrDate[0];
	var DAY = arrDate[1];
	var YEAR = arrDate[2];
	
	
	
	
	if(parseFloat(arrDate[1]) > 12){
	DAY = arrDate[1];
	MONTH = arrDate[0];
	}
	
	if(parseFloat(DAY) && DAY.toString().length==4){
	YEAR = arrDate[0];
	DAY = arrDate[2];
	MONTH = arrDate[1];
	}
	
	
	for(var iSD = 0;iSD < arrMonths.length;iSD++){
	var ShortMonth = arrMonths[iSD].substring(0,3).toLowerCase();
	var MonthPosition = DateToFormat.indexOf(ShortMonth);
		if(MonthPosition > -1){
		MONTH = iSD + 1;
			if(MonthPosition == 0){
			DAY = arrDate[1];
			YEAR = arrDate[2];
			}
		break;
		}
	}
	
	var strTemp = YEAR.toString();
	if(strTemp.length==2){
	
		if(parseFloat(YEAR)>40){
		YEAR = "19" + YEAR;
		}
		else{
		YEAR = "20" + YEAR;
		}
	
	}
	
	
		if(parseInt(MONTH)< 10 && MONTH.toString().length < 2){
		MONTH = "0" + MONTH;
		}
		if(parseInt(DAY)< 10 && DAY.toString().length < 2){
		DAY = "0" + DAY;
		}
		switch (FormatAs){
		case "dd/mm/yyyy":
		return DAY + "/" + MONTH + "/" + YEAR;
		case "mm/dd/yyyy":
		return MONTH + "/" + DAY + "/" + YEAR;
		case "dd/mmm/yyyy":
		return DAY + " " + arrMonths[MONTH -1].substring(0,3) + " " + YEAR;
		case "mmm/dd/yyyy":
		return arrMonths[MONTH -1].substring(0,3) + " " + DAY + " " + YEAR;
		case "dd/mmmm/yyyy":
		return DAY + " " + arrMonths[MONTH -1] + " " + YEAR;	
		case "mmmm/dd/yyyy":
		return arrMonths[MONTH -1] + " " + DAY + " " + YEAR;
		}
	
	return DAY + "/" + strMONTH + "/" + YEAR;;
	
	} //End Function

	
	function DateDiff( start, end, interval, rounding ) {

    var iOut = 0;
    
    // Create 2 error messages, 1 for each argument. 
    var startMsg = "Check the Start Date and End Date\n"
        startMsg += "must be a valid date format.\n\n"
        startMsg += "Please try again." ;
		
    var intervalMsg = "Sorry the dateAdd function only accepts\n"
        intervalMsg += "y, d, h, m OR s intervals.\n\n"
        intervalMsg += "Please try again." ;

    var bufferA = Date.parse( start ) ;
    var bufferB = Date.parse( end ) ;
    	
    // check that the start parameter is a valid Date. 
    if ( isNaN (bufferA) || isNaN (bufferB) ) {
        alert( startMsg ) ;
        return null ;
    }
	
    // check that an interval parameter was not numeric. 
    if ( interval.charAt == 'undefined' ) {
        // the user specified an incorrect interval, handle the error. 
        alert( intervalMsg ) ;
        return null ;
    }
    
    var number = bufferB-bufferA ;
    
    // what kind of add to do? 
    switch (interval.charAt(0))
    {
        case 'y': case 'Y': 
            iOut = parseInt(number / 31536000000) ;
            if(rounding) iOut += parseInt((number % 31536000000)/15768000001) ;
            break ;
        case 'd': case 'D': 
            iOut = parseInt(number / 86400000) ;
            if(rounding) iOut += parseInt((number % 86400000)/43200001) ;
            break ;
        case 'h': case 'H':
            iOut = parseInt(number / 3600000 ) ;
            if(rounding) iOut += parseInt((number % 3600000)/1800001) ;
            break ;
        case 'm': case 'M':
            iOut = parseInt(number / 60000 ) ;
            if(rounding) iOut += parseInt((number % 60000)/30001) ;
            break ;
        case 's': case 'S':
            iOut = parseInt(number / 1000 ) ;
            if(rounding) iOut += parseInt((number % 1000)/501) ;
            break ;
        default:
        // If we get to here then the interval parameter
        // didn't meet the y,d,h,m,s criteria.  Handle
        // the error. 		
        alert(intervalMsg) ;
        return null ;
    }
    
    return iOut ;
}