function isDateString(stringValue) {

	// this function is designed to mimic the "date" portion of the
	// VBScript IsDate() function, allowing dates to be validated
	// with JavaScript in browsers before you run into a problem
	// in ASP pages with date database columns or the VBScript
	// CDate() function; an exception is that string months
	// ("Jan," etc.) are not accepted
	
	// this function does not handle BC dates or dates past 12/31/9999
	
	// you obviously want to strip the comments from production scripts
	
	// create a String object
	var theString = new String(stringValue);
	
	// determine the delimiter character (must be "/" "-" or space)
	var delimiterCharacter
	if ( theString.indexOf('/') > 0 )
		delimiterCharacter = '/';
	else
		if ( theString.indexOf('-') > 0 )
			delimiterCharacter = '-';
		else
			if ( theString.indexOf(' ') > 0 )
				delimiterCharacter = ' ';
			else
				return false;
				
	// split the string into an array of tokens
	var theTokens = theString.split(delimiterCharacter);
	
	// there must be either two or three tokens
	if ( theTokens.length < 2 || theTokens.length > 3 )
		return false;
	
	// convert the tokens to String objects, which will be needed later,
	// stripping a single leading 0
	var tokenIndex;
	for ( tokenIndex = 0; tokenIndex < theTokens.length; tokenIndex++ ) {
		theTokens[tokenIndex] = new String(theTokens[tokenIndex])			
		if ( theTokens[tokenIndex].charAt(0) == '0' )
			theTokens[tokenIndex] = theTokens[tokenIndex].substring(1, theTokens[tokenIndex].length);
	}

	// all of the tokens must be positive integers
	for ( tokenIndex = 0; tokenIndex < theTokens.length; tokenIndex++ ) {
		if ( ! isNonnegativeInteger(theTokens[tokenIndex]) )
			return false;
	}
	
	// we need to identify the year, month, and day tokens
	var numericValue;
	var yearTokenIndex = -1;
	var monthTokenIndex = -1;
	var dayTokenIndex = -1;
	for ( tokenIndex = 0; tokenIndex < theTokens.length; tokenIndex++ ) {
				
		// convert the value
		numericValue = parseInt(theTokens[tokenIndex], 10);
				
		// could this token be a month?
		if ( numericValue <= 12 ) {
				
			// yes; do we already have a month?
			if ( monthTokenIndex == -1 ) {
					
				// no; assign this token to the month and continue
				monthTokenIndex = tokenIndex;
				continue;
			}
			else {
						
				// we already have a month; this token could
				// also be the day; do we already have a day?
				if ( dayTokenIndex == -1 ) {
					
					// no; assign this token to the day and continue
					dayTokenIndex = tokenIndex;
					continue;
				}
				else {
						
					// we already have a day; this token could
					// also be the year; do we alreay have a year?
					if ( yearTokenIndex == -1 ) {
					
						// no; assign this token to the year and continue
						dayTokenIndex = tokenIndex;
						continue;
					}
				}
			}
		}
		else {
					
			// the value is too large for a month;
			// could this token be a day?
			if ( numericValue <= 31 ) {
					
				// yes; do we already have a day?
				if ( dayTokenIndex == -1 ) {
					
					// no; assign this token to the day and continue
					dayTokenIndex = tokenIndex;
					continue;
				}
				else {
						
					// we already have a day; this token could
					// also be the year; do we alreay have a year?
					if ( yearTokenIndex == -1 ) {
					
						// no; assign this token to the year and continue
						dayTokenIndex = tokenIndex;
						continue;
					}
				}
			}
			else {
					
				// the value is too large for a day;
				// could this token be a year?
				if ( numericValue <= 9999 ) {
				
					// yes; do we already have a year?
					if ( yearTokenIndex == -1 ) {
					
						// no; assign this token to the year
						yearTokenIndex = tokenIndex;
					}
				}
			}
		}
	}	// end of for loop
	
	// evaluate, based on the number of tokens
	if ( theTokens.length == 2 ) {
		
		// two tokens can be either a month/year combination or a month/day
		// combination with the current year assumed; either way, we must have
		// a month
		if ( monthTokenIndex == -1 )
			
			// no month
			return false;
			
		// do we have a year?
		if ( ! (yearTokenIndex == -1) ) {
		
			// yes; month/year combination; must be okay
			return true;
		}
		else
			
			// no year; do we have a day?
			if ( ! (dayTokenIndex == -1) ) {
			
				// yes; month/day combination; get the current year
				var today = new Date();
				var currentYear = today.getYear();

				// make sure it's a valid date (we were testing days using
				// 31, and that might be too many for the month)
				return isDate(currentYear, theTokens[monthTokenIndex], theTokens[dayTokenIndex]);
			}
			else
			
				// we have neither a year nor a day
				return false;
	}
	else {
		
		// three tokens; we should have found tokens for year, month, and day
		if ( yearTokenIndex == -1 || monthTokenIndex == -1 || dayTokenIndex == -1 )
			
			// missing one or more
			return false;
		else
			
			// found all; however, VBScript can only handle the following sequences
			if ( monthTokenIndex == 0 ) {
			
				// must be m/d/y
				if ( dayTokenIndex != 1 || yearTokenIndex != 2)
					return false;
			}
			else
				if ( dayTokenIndex == 0 ) {
			
					// must be d/m/y
					if ( monthTokenIndex != 1 || yearTokenIndex != 2)
						return false;
				}
				else
					if ( yearTokenIndex == 0 ) {
			
						// must be y/m/d
						if ( monthTokenIndex != 1 || dayTokenIndex != 2)
							return false;
					}
					else
					
						// something is wrong
						return false;
			
			// make sure it's a valid date (we were testing days using a value
			// of 31, and that might be too many for the actual month)
			return isDate(theTokens[yearTokenIndex], theTokens[monthTokenIndex], theTokens[dayTokenIndex]);
	}
}


// most of the following was derived from Netscape's FormChek.js
// library, which should be reviewed for documentation and comments

var daysInMonth = makeArray(12);
daysInMonth[1] = 31;
daysInMonth[2] = 29;
daysInMonth[3] = 31;
daysInMonth[4] = 30;
daysInMonth[5] = 31;
daysInMonth[6] = 30;
daysInMonth[7] = 31;
daysInMonth[8] = 31;
daysInMonth[9] = 30;
daysInMonth[10] = 31;
daysInMonth[11] = 30;
daysInMonth[12] = 31;

var whitespace = " \t\n\r";

function charInString(c, s) {
	for (i = 0; i < s.length; i++) {
		if (s.charAt(i) == c)
			return true;
    }
    return false
}

function daysInFebruary(year) {
    return ( ((year % 4 == 0) && ((!(year % 100 == 0)) || (year % 400 == 0))) ? 29 : 28 );
}

function isDate(year, month, day) {
    if ( ! ( isYear(year) && isMonth(month) && isDay(day) ) ) return false;
    var intYear = parseInt(year);
    var intMonth = parseInt(month);
    var intDay = parseInt(day);
    if ( intDay > daysInMonth[intMonth] ) return false; 
    if ( ( intMonth == 2 ) && ( intDay > daysInFebruary(intYear) ) ) return false;
    return true;
}

function isDay(s) {
    return isIntegerInRange(s, 1, 31);
}

function isDigit(c) {
	return ( ( c >= "0" ) && ( c <= "9" ) )
}

function isInteger(s) {
	var i;
    for ( i = 0; i < s.length; i++ )
    {   
        var c = s.charAt(i);
        if ( ! isDigit(c) ) return false;
    }
    return true;
}

function isIntegerInRange(s, a, b) {
    if ( ! isInteger(s) ) return false;
    var num = parseInt (s);
    return ( ( num >= a ) && ( num <= b ) );
}

function isMonth(s) {
    return isIntegerInRange (s, 1, 12);
}

function isNonnegativeInteger(s) {
    return ( isSignedInteger(s) && ( parseInt(s) >= 0 ) );
}

function isSignedInteger(s) {
    var startPos = 0;
    if ( ( s.charAt(0) == "-" ) || ( s.charAt(0) == "+" ) )
       startPos = 1;    
    return ( isInteger(s.substring(startPos, s.length)) )
}

function isYear(s) {
	if ( ! isNonnegativeInteger(s) ) return false;
    //require 4 digit year: return ( (s.length == 2) || (s.length == 4) );
	if (s > 1900 && s < 2200)
		return true;
	else
		return false;
}

function lTrim(s) {
	var i = 0;
    while ( (i < s.length) && charInString(s.charAt(i), whitespace) )
       i++;
    return s.substring(i, s.length);
}

function makeArray(n) {
   for ( var i = 1; i <= n; i++ ) {
      this[i] = 0
   } 
   return this
}

function rTrim(s) {
	var i = 0;
    while ( (i < s.length) && charInString(s.charAt(i), whitespace) )
       i++;
    return s.substring(i, s.length);
}

function trim(s) {
	return lTrim(rTrim(s));
}