var dtCh= "/";
	var minYear=1900;
	var maxYear=2100;

	//=========================================================
	function isInteger(s){
	//=========================================================
		var i;
	    for (i = 0; i < s.length; i++){   
	        // Check that current character is number.
	        var c = s.charAt(i);
	        if (((c < "0") || (c > "9"))) return false;
	    }
	    // All characters are numbers.
	    return true;
	}

	//=========================================================
	function stripCharsInBag(s, bag){
	//=========================================================
		var i;
	    var returnString = "";
	    // Search through string's characters one by one.
	    // If character is not in bag, append to returnString.
	    for (i = 0; i < s.length; i++){   
	        var c = s.charAt(i);
	        if (bag.indexOf(c) == -1) returnString += c;
	    }
	    return returnString;
	}
	
	//=========================================================
	function daysInFebruary (year){
	//=========================================================
		// February has 29 days in any year evenly divisible by four,
	    // EXCEPT for centurial years which are not also divisible by 400.
	    return (((year % 4 == 0) && ( (!(year % 100 == 0)) || (year % 400 == 0))) ? 29 : 28 );
	}

	//=========================================================
	function DaysArray(n) {
	//=========================================================
		for (var i = 1; i <= n; i++) {
			this[i] = 31
			if (i==4 || i==6 || i==9 || i==11) {this[i] = 30}
			if (i==2) {this[i] = 29}
	   } 
	   return this
	}

	//=========================================================
	function isDate(dtStr){
	//=========================================================
		var daysInMonth = DaysArray(12)
		var pos1=dtStr.indexOf(dtCh)
		var pos2=dtStr.indexOf(dtCh,pos1+1)
		var strMonth=dtStr.substring(pos1+1,pos2)
		var strDay=dtStr.substring(0,pos1)
		var strYear=dtStr.substring(pos2+1)

		if (dtStr != '') {
		strYr=strYear
		if (strDay.charAt(0)=="0" && strDay.length>1) strDay=strDay.substring(1)
		if (strMonth.charAt(0)=="0" && strMonth.length>1) strMonth=strMonth.substring(1)
		for (var i = 1; i <= 3; i++) {
			if (strYr.charAt(0)=="0" && strYr.length>1) strYr=strYr.substring(1)
		}
		month=parseInt(strMonth)
		day=parseInt(strDay)
		year=parseInt(strYr)
		if (pos1==-1 || pos2==-1){
			alert("A data deve ser no formato : dd/mm/aaaa")
			return false
		}
		if (strMonth.length<1 || month<1 || month>12){
			alert("Męs inválido")
			return false
		}
		if (strDay.length<1 || day<1 || day>31 || (month==2 && day>daysInFebruary(year)) || day > daysInMonth[month]){
			alert("Dia inválido")
			return false
		}
		if (strYear.length != 4 || year==0 || year<minYear || year>maxYear){
			alert("O ano deve estar entre "+minYear+" e "+maxYear)
			return false
		}
		if (dtStr.indexOf(dtCh,pos2+1)!=-1 || isInteger(stripCharsInBag(dtStr, dtCh))==false){
			alert("Data inválida")
			return false
		}
		}
		else {
			return false
		}
	return true
	}

	
	<!-- Begin
	
	var isNav4 = false, isNav5 = false, isIE4 = false
	var strSeperator = "/"; 
	var vDateType = 1; 		// Formato da Data
	//                1 = mm/dd/yyyy
	//                2 = yyyy/dd/mm  
	//                3 = dd/mm/yyyy
	var vYearType = 4; 	 //Set to 2 or 4 for number of digits in the year for Netscape
	var err = 0; 			// Set the error code to a default of zero
	var vDateTemp;
	if(navigator.appName == "Netscape") {
	if (navigator.appVersion < "5") {
	isNav4 = true;
	isNav5 = false;
	}
	else
	if (navigator.appVersion > "4") {
	isNav4 = false;
	isNav5 = true;
	   }
	}
	else isIE4 = true;
	function DateFormat(vDateName, vDateValue, e, dateCheck, dateType) {
	vDateType = dateType;
	
	//////////////////////////////////////////////////////////////////////////////////////
	// vDateName = object name
	// vDateValue = value in the field being checked
	// e = event
	// dateCheck 
	//       True  = Verify that the vDateValue is a valid date
	//       False = Format values being entered into vDateValue only
	// vDateType
	//       1 = mm/dd/yyyy
	//       2 = yyyy/mm/dd
	//       3 = dd/mm/yyyy
	//Enter a tilde sign for the first number and you can check the variable information.
	//////////////////////////////////////////////////////////////////////////////////////
	
	if (vDateValue == "~") {
	alert("AppVersion = "+navigator.appVersion+" \nNav. 4 Version = "+isNav4+" \nNav. 5 Version = "+isNav5+" \nIE Version = "+isIE4+" \nYear Type = "+vYearType+" \nDate Type = "+vDateType+" \nSeparator = "+strSeperator);
	vDateName.value = "";
	vDateName.focus();
	return true;
	} 
	var whichCode = (window.Event) ? e.which : e.keyCode;
	
	// Check to see if a seperator is already present.
	// bypass the date if a seperator is present and the length greater than 8
	if (vDateValue.length > 8 && isNav4)
	{
		if ((vDateValue.indexOf("-") >= 1) || (vDateValue.indexOf("/") >= 1)) return true;
	}
	
	// Eliminate all the ASCII codes that are not valid
	var alphaCheck = " abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ/-";
	
	if (alphaCheck.indexOf(vDateValue) >= 1)
	{
		if (isNav4)
		{
			vDateName.value = "";
			vDateName.focus();
			vDateName.select();
			return false;
		}
		else
		{
			vDateName.value = vDateName.value.substr(0, (vDateValue.length-1));
			return false;
	
	   }
	}
	
	if (whichCode == 8) //Ignore the Netscape value for backspace. IE has no value
		return false;
	else
	 {
		//Create numeric string values for 0123456789/
		//The codes provided include both keyboard and keypad values
		var strCheck = '47,48,49,50,51,52,53,54,55,56,57,58,59,95,96,97,98,99,100,101,102,103,104,105';
		if (strCheck.indexOf(whichCode) != -1)
	   {
			if (isNav4)
			{
				if (((vDateValue.length < 6 && dateCheck) || (vDateValue.length == 7 && dateCheck)) && (vDateValue.length >=1))
				{
					alert("Data Inválida\nPor favor digite novamente.");
					vDateName.value = "";
					vDateName.focus();
					vDateName.select();
					return false;
				}
				if (vDateValue.length == 6 && dateCheck)
				{
					var mDay = vDateName.value.substr(2,2);
					var mMonth = vDateName.value.substr(0,2);
					var mYear = vDateName.value.substr(4,4);
					//Turn a two digit year into a 4 digit year
					if (mYear.length == 2 && vYearType == 4)
					{
						var mToday = new Date();
						//If the year is greater than 30 years from now use 19, otherwise use 20
						var checkYear = mToday.getFullYear() + 30; 
						var mCheckYear = '20' + mYear;
						if (mCheckYear >= checkYear) mYear = '19' + mYear;
						else mYear = '20' + mYear;
					}
					var vDateValueCheck = mMonth+strSeperator+mDay+strSeperator+mYear;
					if (!dateValid(vDateValueCheck))
					{
						alert("Data Inválida\nPor favor digite novamente.");
						vDateName.value = "";
						vDateName.focus();
						vDateName.select();
						return false;
					}
					return true;
				}
				else
				{
					// Reformat the date for validation and set date type to a 1
					if (vDateValue.length >= 8  && dateCheck)
					{
						// mmddyyyy
						if (vDateType == 1)
						{
							var mDay = vDateName.value.substr(2,2);
							var mMonth = vDateName.value.substr(0,2);
							var mYear = vDateName.value.substr(4,4)
							vDateName.value = mMonth+strSeperator+mDay+strSeperator+mYear;
						}
						// yyyymmdd
						if (vDateType == 2)
						{
							var mYear = vDateName.value.substr(0,4)
							var mMonth = vDateName.value.substr(4,2);
							var mDay = vDateName.value.substr(6,2);
							vDateName.value = mYear+strSeperator+mMonth+strSeperator+mDay;
						}
						// ddmmyyyy
						if (vDateType == 3)
						{
							var mMonth = vDateName.value.substr(2,2);
							var mDay = vDateName.value.substr(0,2);
							var mYear = vDateName.value.substr(4,4)
							vDateName.value = mDay+strSeperator+mMonth+strSeperator+mYear;
						}
						//Create a temporary variable for storing the DateType and change
						//the DateType to a 1 for validation.
						var vDateTypeTemp = vDateType;
						vDateType = 1;
						var vDateValueCheck = mMonth+strSeperator+mDay+strSeperator+mYear;
						if (!dateValid(vDateValueCheck))
						{
							alert("Data Inválida\nPor favor digite novamente.");
							vDateType = vDateTypeTemp;
							vDateName.value = "";
							vDateName.focus();
							vDateName.select();
							return false;
						}	
						vDateType = vDateTypeTemp;
						return true;
				   }
					else
					{
						if (((vDateValue.length < 8 && dateCheck) || (vDateValue.length == 9 && dateCheck)) && (vDateValue.length >=1))
						{
							alert("Data Inválida\nPor favor digite novamente.");
							vDateName.value = "";
							vDateName.focus();
							vDateName.select();
							return false;
						}
					}
			   }  
		}
		else
		{
			// Non isNav Check
			
			if (vDateType == 3)
			{
			   if ( vDateName.value.length > 10 && whichCode != 9 && ! dateCheck){
			   vDateName.value = vDateName.value.substr(0,vDateName.value.length-1);
			   return false;
			   }
			}
			
			if (((vDateValue.length < 8 && dateCheck) || (vDateValue.length == 9 && dateCheck)) && (vDateValue.length >=1))
			{
				alert("Data Inválida\nPor favor digite novamente.");
				vDateName.value = "";
				vDateName.focus();
				return true;
			}
			// Reformat date to format that can be validated. mm/dd/yyyy
			if (vDateValue.length >= 8 && dateCheck) {
				// Additional date formats can be entered here and parsed out to
				// a valid date format that the validation routine will recognize.
				// mm/dd/yyyy
				if (vDateType == 1)
				{
					var mMonth = vDateName.value.substr(0,2);
					var mDay = vDateName.value.substr(3,2);
					var mYear = vDateName.value.substr(6,4)
				}
				// yyyy/mm/dd
				if (vDateType == 2)
				{
					var mYear = vDateName.value.substr(0,4)
					var mMonth = vDateName.value.substr(5,2);
					var mDay = vDateName.value.substr(8,2);
				}
				// dd/mm/yyyy
				if (vDateType == 3)
				{
					var mDay = vDateName.value.substr(0,2);
					var mMonth = vDateName.value.substr(3,2);
					var mYear = vDateName.value.substr(6,4)
				}
	
				// Create temp. variable for storing the current vDateType
				var vDateTypeTemp = vDateType;
				// Change vDateType to a 1 for standard date format for validation
				// Type will be changed back when validation is completed.
				vDateType = 1;
				// Store reformatted date to new variable for validation.
				var vDateValueCheck = mMonth+strSeperator+mDay+strSeperator+mYear;
				if (vDateValueCheck.length >= 8 && dateCheck)
				{
					//Turn a two digit year into a 4 digit year
					if (mYear.length == 2 && vYearType == 4)
					{
						var mToday = new Date();
						//If the year is greater than 30 years from now use 19, otherwise use 20
						var checkYear = mToday.getFullYear() + 80; 
						var mCheckYear = '20' + mYear;
						if (mCheckYear >= checkYear) mYear = '19' + mYear;
						else mYear = '20' + mYear;
					}
					vDateValueCheck = mMonth+strSeperator+mDay+strSeperator+mYear;
				} 
				if (!dateValid(vDateValueCheck))
				{
					alert("Data Inválida\nPor favor digite novamente.");
					vDateType = vDateTypeTemp;
					vDateName.value = "";
					vDateName.focus();
					return true;
				}
				
				
				if ( dateType == 3 )
				{
					vDateName.value = mDay+strSeperator+mMonth+strSeperator+mYear;
			   }		
				vDateType = vDateTypeTemp;
				return true;
			}
			else
			{
				if (vDateType == 1)
				{
					if (vDateValue.length == 2)
					{
						vDateName.value = vDateValue+strSeperator;
					}
					if (vDateValue.length == 5)
					{
						vDateName.value = vDateValue+strSeperator;
					}
				}
				if (vDateType == 2)
				{
					if (vDateValue.length == 4)  
					{
						vDateName.value = vDateValue+strSeperator;
					}
					if (vDateValue.length == 7)
					{
						vDateName.value = vDateValue+strSeperator;
					}
				}
				if (vDateType == 3)
				{
					if (vDateValue.length == 2)
					{
						vDateName.value = vDateValue+strSeperator;
					}
					if (vDateValue.length == 5)
					{
						vDateName.value = vDateValue+strSeperator;
					}
				}
				return true;
			}
		}
		if (vDateValue.length == 10 && dateCheck)
		{
			if (!dateValid(vDateName))
			{
				// Un-comment the next line of code for debugging the dateValid() function error messages
				//alert(err);  
				alert("Data Inválida\nPor favor digite novamente.");
				vDateName.focus();
				vDateName.select();
			}
		}
		return false;
	}
	else
	{
		// If the value is not in the string return the string minus the last
		// key entered.
		if (isNav4)
		{
			vDateName.value = "";
			vDateName.focus();
			vDateName.select();
			return false;
		}
		else
		{
			if (whichCode != 4 && whichCode != 19 && whichCode != 45 && whichCode != 46 && whichCode !=16 && !(whichCode >=35 && whichCode <=40) )
			{
				vDateName.value = vDateName.value.substr(0, (vDateValue.length-1));
				return false;
			}	
	   }
	}
	}
	}
	
	
	function dateValid(objName) {
	var strDate;
	var strDateArray;
	var strDay;
	var strMonth;
	var strYear;
	var intday;
	var intMonth;
	var intYear;
	var booFound = false;
	var datefield = objName;
	var strSeparatorArray = new Array("-"," ","/",".");
	var intElementNr;
	// var err = 0;
	var strMonthArray = new Array(12);
	strMonthArray[0] = "Jan";
	strMonthArray[1] = "Fev";
	strMonthArray[2] = "Mar";
	strMonthArray[3] = "Abr";
	strMonthArray[4] = "Mai";
	strMonthArray[5] = "Jun";
	strMonthArray[6] = "Jul";
	strMonthArray[7] = "Ago";
	strMonthArray[8] = "Set";
	strMonthArray[9] = "Out";
	strMonthArray[10] = "Nov";
	strMonthArray[11] = "Dez";
	//strDate = datefield.value;
	strDate = objName;
	
	if (strDate.length < 1)
	{
		return true;
	}
	
	for (intElementNr = 0; intElementNr < strSeparatorArray.length; intElementNr++)
	{
		if (strDate.indexOf(strSeparatorArray[intElementNr]) != -1)
		{
			strDateArray = strDate.split(strSeparatorArray[intElementNr]);
			if (strDateArray.length != 3)
			{
				err = 1;
				return false;
			}
			else
			{
				strDay = strDateArray[0];
				strMonth = strDateArray[1];
				strYear = strDateArray[2];
			}
			booFound = true;
	   }
	}
	
	if (booFound == false)
	{
		if (strDate.length>5)
		{
			strDay = strDate.substr(0, 2);
			strMonth = strDate.substr(2, 2);
			strYear = strDate.substr(4);
	   }
	}
	//Adjustment for short years entered
	if (strYear.length == 2)
	{
		strYear = '20' + strYear;
	}
	strTemp = strDay;
	strDay = strMonth;
	strMonth = strTemp;
	intday = parseInt(strDay, 10);
	if (isNaN(intday))
	{
		err = 2;
		return false;
	}
	intMonth = parseInt(strMonth, 10);
	if (isNaN(intMonth))
	{
		for (i = 0;i<12;i++)
		{
			if (strMonth.toUpperCase() == strMonthArray[i].toUpperCase())
			{
				intMonth = i+1;
				strMonth = strMonthArray[i];
				i = 12;
			}
		}
		if (isNaN(intMonth))
		{
			err = 3;
			return false;
	   }
	}
	intYear = parseInt(strYear, 10);
	if (isNaN(intYear))
	{
		err = 4;
		return false;
	}
	if (intMonth>12 || intMonth<1)
	{
		err = 5;
		return false;
	}
	if ((intMonth == 1 || intMonth == 3 || intMonth == 5 || intMonth == 7 || intMonth == 8 || intMonth == 10 || intMonth == 12) && (intday > 31 || intday < 1))
	{
		err = 6;
		return false;
	}
	if ((intMonth == 4 || intMonth == 6 || intMonth == 9 || intMonth == 11) && (intday > 30 || intday < 1))
	{
		err = 7;
		return false;
	}
	if (intMonth == 2)
	{
		if (intday < 1)
		{
			err = 8;
			return false;
		}
		if (LeapYear(intYear) == true)
		{
			if (intday > 29)
			{
				err = 9;
				return false;
			}
		}
		else
		{
			if (intday > 28)
			{
				err = 10;
				return false;
	      }
	   }
	}
	return true;
	}
	
	function LeapYear(intYear) {
	if (intYear % 100 == 0)
	{
		if (intYear % 400 == 0)
		{
			return true;
	   }
	}
	else
	{
		if ((intYear % 4) == 0)
		{
			return true;
	   }
	}
	return false;
	}