function FieldChecker()
{
	//Variables
	var msgMaxRows = "Het maximum aantal rijen voor het veld <FriendlyName> is <maxRows>.";
	var msgMaxChars = "Het maximum aantal karakters voor het veld <FriendlyName> is <maxChars>.";
	var msgRequired = "Het veld <FriendlyName> is een verplicht veld.";
	var msgIncorrectExtension = "Het uploaden van het bestand <File> is niet toegestaan in het veld <FriendlyName>.\nDe volgende bestandtypen zijn wel toegstaan: <Extensions>.";
	var msgIncorrectMailAddress = "Het veld <FriendlyName> bevat een ongeldig mailadres."
	var msgIncorrectPostalCode = "Het veld <FriendlyName> bevat een ongeldige postcode."
	var msgIncorrectPercentage = "Het veld <FriendlyName> moet een percentage bevatten tussen <minValue> en <maxValue>."
	var RequiredFieldColor = "#FFFFFF";
	
	//Properties
	this.Fields = new Array(75); //Used for storing checkFields
	this.FileFields = new Array();
	this.FieldCount = 0; //Current fieldCount
	// initialize the member function references
	// for the class prototype
	if (typeof(_FieldChecker_prototype_called) == 'undefined')
	{
		_FieldChecker_prototype_called = true;
	    	FieldChecker.prototype.addField = _addField;
	    	FieldChecker.prototype.addFileField = _addFileField;
		FieldChecker.prototype.checkFields = _checkFields;
		FieldChecker.prototype.setMsgMaxRows = _setMsgMaxRows;
		FieldChecker.prototype.setMsgMaxChars = _setMsgMaxChars;
		FieldChecker.prototype.setMsgRequired = _setMsgRequired;
		FieldChecker.prototype.setExtensions = _setExtensions;
		FieldChecker.prototype.setMsgIncorrectExtension = _setMsgIncorrectExtension;
		FieldChecker.prototype.clearAllFields = _clearAllFields;
		FieldChecker.prototype.getFieldByName = _getFieldByName;
		FieldChecker.prototype.setMsgIncorrectMailAddress = _setMsgIncorrectMailAddress;
		FieldChecker.prototype.setMsgIncorrectPostalCode = _setMsgIncorrectPostalCode;
		FieldChecker.prototype.setMsgIncorrectPercentage = _setMsgIncorrectPercentage;
		FieldChecker.prototype.setRequiredFieldColor = _setRequiredFieldColor;
	}
	function _setMsgIncorrectMailAddress(Msg)
	{
		msgIncorrectMailAddress = Msg;
	}
	function _getFieldByName(Name)
	{
		for (var i = 1; i <= this.FieldCount; i++)
		{
			if (this.Fields[i].Fieldname == Name)
			{
				return this.Fields[i];
			}
		}
	}
	function _addField(Fieldname, FriendlyName, maxRows, maxChars, Required)
	{
		if (document.getElementsByName(Fieldname).length > 0)
		{
			this.FieldCount++;
			this.Fields[this.FieldCount] = new checkField(Fieldname, FriendlyName, maxRows, maxChars, Required);
			if (Required == true)
				document.getElementsByName(Fieldname)[0].style.backgroundColor = RequiredFieldColor;
		}
		else
		{
			//alert("The field " + Fieldname + " does not exist...");
		}
	}			
	function _addFileField(Fieldname, FriendlyName, Extensions, Required)
	{
		if (document.getElementsByName(Fieldname).length > 0)
		{			
			this.FileFields[this.FileFields.length] = new checkFileField(Fieldname, FriendlyName, Extensions, Required);			
			if (Required == true)
				document.getElementsByName(Fieldname)[0].style.backgroundColor = RequiredFieldColor;
		}
		else
		{
			//alert("The field " + Fieldname + " does not exist...");
		}
	}
	function _clearAllFields()
	{
		for (var i = 1; i <= this.FieldCount; i++)
		{
			document.getElementsByName(this.Fields[i].Fieldname)[0].value = "";
		}
	}
	function _checkFields()
	{
		//Loop through Fields in FieldChecker
		for (var i = 1; i <= this.FieldCount; i++)
		{
			//Check Maximum Number of Rows
			if (this.Fields[i].maxRows > 0)
			{
				if (getRowCount(this.Fields[i].Fieldname) > this.Fields[i].maxRows)
				{
					var ErrorMsg = replaceSubstring(msgMaxRows, "<FriendlyName>", this.Fields[i].FriendlyName);
					ErrorMsg = replaceSubstring(ErrorMsg, "<maxRows>", "" + this.Fields[i].maxRows);
					alert(ErrorMsg);
					document.getElementsByName(this.Fields[i].Fieldname)[0].focus();
					return false;
				}	
			}
			
			//Check Maximum Number of Characters
			if (this.Fields[i].maxChars > 0)
			{
				if (document.getElementsByName(this.Fields[i].Fieldname)[0].value.length > this.Fields[i].maxChars)
				{
					var ErrorMsg = replaceSubstring(msgMaxChars, "<FriendlyName>", this.Fields[i].FriendlyName);
					ErrorMsg = replaceSubstring(ErrorMsg, "<maxChars>", "" + this.Fields[i].maxChars);
					alert(ErrorMsg);
					document.getElementsByName(this.Fields[i].Fieldname)[0].focus();
					return false;
				}
			}
			
			//Check Field is Required/Empty
			if (this.Fields[i].Required == true)
			{
				if (document.getElementsByName(this.Fields[i].Fieldname)[0].value == "")
				{
					var ErrorMsg = replaceSubstring(msgRequired, "<FriendlyName>", this.Fields[i].FriendlyName);
					alert(ErrorMsg);
					document.getElementsByName(this.Fields[i].Fieldname)[0].focus();
					return false;
				}
			}
			//Check Field contains file with Correct Extension
			if (document.getElementsByName(this.Fields[i].Fieldname)[0].type == "file")
			{
				var CorrectExtension = false;
				var strExtensions = ""
				var Extension = document.getElementsByName(this.Fields[i].Fieldname)[0].value;
				if (Extension != "")
				{
					Extension = Extension.substring(Extension.length-4,Extension.length);
				
					for (var j=0;j<Extensions.length;j++)
					{
						strExtensions+=Extensions[j] + ","
						if (Extension.toUpperCase() == Extensions[j].toUpperCase())
							CorrectExtension = true;
					}
					if (CorrectExtension == false)
					{
						var ErrorMsg = replaceSubstring(msgIncorrectExtension, "<FriendlyName>", this.Fields[i].FriendlyName);
						ErrorMsg = replaceSubstring(ErrorMsg, "<Extensions>", strExtensions.substring(0,strExtensions.length-1));
						ErrorMsg = replaceSubstring(ErrorMsg, "<File>", document.getElementsByName(this.Fields[i].Fieldname)[0].value);
						alert(ErrorMsg);
						document.getElementsByName(this.Fields[i].Fieldname)[0].focus();
						return false;
					}
				}
			}
			//Check correct MailAddress
			if (this.Fields[i].isMail == true)
			{
				var EMailVal = document.getElementsByName(this.Fields[i].Fieldname)[0].value;
				var filter  = /^([a-zA-Z0-9_\.\-])+\@(([a-zA-Z0-9\-])+\.)+([a-zA-Z0-9]{2,4})+$/;
				if (!filter.test(EMailVal)) 
				{
					alert(replaceSubstring(msgIncorrectMailAddress, "<FriendlyName>", this.Fields[i].FriendlyName))
					document.getElementsByName(this.Fields[i].Fieldname)[0].focus();
					return false;
				}
			}
			//Check correct PostalCode
			if (this.Fields[i].isPostalCode == true)
			{
				var newString="";
				var iError = false;
				for (var j=0;j<document.getElementsByName(this.Fields[i].Fieldname)[0].value.length;j++)
				{
					var currChar = document.getElementsByName(this.Fields[i].Fieldname)[0].value.substring(j,j+1).toLowerCase();
					if (((currChar >= "a") & (currChar <= "z")) | ((currChar >= "0") & (currChar <= "9")))
						newString += currChar.toLowerCase();							
				}
				
				var re = /^\d{4}[a-z]{2}$/ //Check for 4 digits folowed by 2 chars
				if (newString.search(re)==-1) 
				{
					alert(replaceSubstring(msgIncorrectPostalCode, "<FriendlyName>", this.Fields[i].FriendlyName))
					document.getElementsByName(this.Fields[i].Fieldname)[0].focus();
					return false;
				}
				else
				{
					document.getElementsByName(this.Fields[i].Fieldname)[0].value = newString.toUpperCase();	
				}
			}
			//Check correct Percentage
			if (this.Fields[i].isPercentage == true)
			{
				var Percentage = document.getElementsByName(this.Fields[i].Fieldname)[0].value;
				var re = /^\d{1,9999}$/ //Check for 4 digits only
				var iError = false;
				if (Percentage.search(re)!=-1) 
				{
					if ((Percentage < this.Fields[i].minPercentage) | (Percentage > this.Fields[i].maxPercentage)) iError = true
				}
				else iError = true;
				if (iError == true)
				{
					var ErrMessage = "";
					ErrMessage = replaceSubstring(msgIncorrectPercentage, "<FriendlyName>", this.Fields[i].FriendlyName);
					ErrMessage = replaceSubstring(ErrMessage,"<minValue>","" + this.Fields[i].minPercentage);
					ErrMessage = replaceSubstring(ErrMessage,"<maxValue>","" + this.Fields[i].maxPercentage);
					alert(ErrMessage);
					document.getElementsByName(this.Fields[i].Fieldname)[0].focus();
					return false;
				}
			}
			//Check correct number
			if (this.Fields[i].isNumeric == true)
			{
				var getal = document.getElementsByName(this.Fields[i].Fieldname)[0].value;
				var re = /^\d{*}[,]{0,1}\d{*}$/ //Check for 4 digits folowed by 2 chars
 
			}
		}
		
		// check file fields		
		for (var i=0; i < this.FileFields.length; i++)
		{	
			// controleer of veld verplicht is
			if (document.getElementsByName(this.FileFields[i].Fieldname)[0].value == "" && this.FileFields[i].Required)
			{
				var ErrorMsg = replaceSubstring(msgRequired, "<FriendlyName>", this.FileFields[i].FriendlyName);
				alert(ErrorMsg);
				document.getElementsByName(this.FileFields[i].Fieldname)[0].focus();
				return false;
			}
			
			if(document.getElementsByName(this.FileFields[i].Fieldname)[0].value != "")
			{
				// controleer extensie				
				var FilePath = document.getElementsByName(this.FileFields[i].Fieldname)[0].value;			
				var FileExt = FilePath.substring(FilePath.lastIndexOf(".")+1, FilePath.length);
				var isValidExtension = false;
				for (var ix=0; ix < this.FileFields[i].Extensions.length; ix++)
				{
					if(FileExt.toLowerCase() == replaceSubstring(this.FileFields[i].Extensions[ix].toLowerCase(), " ",""))
						isValidExtension = true;								
				}
				if(!isValidExtension)
				{
					var ErrorMsg = replaceSubstring(msgIncorrectExtension, "<FriendlyName>", this.FileFields[i].FriendlyName);
					ErrorMsg = replaceSubstring(ErrorMsg, "<Extensions>", this.FileFields[i].ExtensionsTXT);
					ErrorMsg = replaceSubstring(ErrorMsg, "<File>", document.getElementsByName(this.FileFields[i].Fieldname)[0].value);
					alert(ErrorMsg);
					document.getElementsByName(this.FileFields[i].Fieldname)[0].focus();
					return false;										
				}				
			}
			
		}
		//Specific checks from JS Header of HTML document in which FieldChecker is used
		try
		{
			return checkFieldsEx();
		}
		catch(e){}
		return true; //All fields oké
	}
	function getRowCount(field)
	{
		var text = document.getElementsByName(field)[0].value;
		var split = text.split("\n");
		return split.length;
	}
	function _setMsgMaxRows(Msg)
	{
		msgMaxRows = Msg;
	}
	
	function _setMsgMaxChars(Msg)
	{
		msgMaxChars = Msg;
	}
	function _setMsgRequired(Msg)
	{
		msgRequired = Msg;
	}
	function _setExtensions(passExt)
	{
		Extensions = passExt;
	}
	function _setMsgIncorrectExtension(Msg)
	{
		msgIncorrectExtension = Msg;
	}
	function _setMsgIncorrectPostalCode(Msg)
	{
		msgIncorrectPostalCode = Msg;
	}
	function _setMsgIncorrectPercentage(Msg)
	{
		msgIncorrectPercentage = Msg;
	}
	function _setRequiredFieldColor(Color)
	{
		RequiredFieldColor = Color;
		for (var i = 1; i <= this.FieldCount; i++)
		{
			if (this.Fields[i].Required == true)
				document.getElementsByName(this.Fields[i].Fieldname)[0].style.backgroundColor = RequiredFieldColor;
		}
	}
	function replaceSubstring(inputString, fromString, toString) {
	   // Goes through the inputString and replaces every occurrence of fromString with toString
	   var temp = inputString;
	   if (fromString == "") {
	      return inputString;
	   }
	   if (toString.indexOf(fromString) == -1) { // If the string being replaced is not a part of the replacement string (normal situation)
	      while (temp.indexOf(fromString) != -1) {
	         var toTheLeft = temp.substring(0, temp.indexOf(fromString));
	         var toTheRight = temp.substring(temp.indexOf(fromString)+fromString.length, temp.length);
	         temp = toTheLeft + toString + toTheRight;
	      }
	   } else { // String being replaced is part of replacement string (like "+" being replaced with "++") - prevent an infinite loop
	      var midStrings = new Array("~", "`", "_", "^", "#");
	      var midStringLen = 1;
	      var midString = "";
	      // Find a string that doesn't exist in the inputString to be used
	      // as an "inbetween" string
	      while (midString == "") {
	         for (var i=0; i < midStrings.length; i++) {
	            var tempMidString = "";
	            for (var j=0; j < midStringLen; j++) { tempMidString += midStrings[i]; }
	            if (fromString.indexOf(tempMidString) == -1) {
	               midString = tempMidString;
	               i = midStrings.length + 1;
	            }
	         }
	      } // Keep on going until we build an "inbetween" string that doesn't exist
	      // Now go through and do two replaces - first, replace the "fromString" with the "inbetween" string
	      while (temp.indexOf(fromString) != -1) {
	         var toTheLeft = temp.substring(0, temp.indexOf(fromString));
	         var toTheRight = temp.substring(temp.indexOf(fromString)+fromString.length, temp.length);
	         temp = toTheLeft + midString + toTheRight;
	      }
	      // Next, replace the "inbetween" string with the "toString"
	      while (temp.indexOf(midString) != -1) {
	         var toTheLeft = temp.substring(0, temp.indexOf(midString));
	         var toTheRight = temp.substring(temp.indexOf(midString)+midString.length, temp.length);
	         temp = toTheLeft + toString + toTheRight;
	      }
	   } // Ends the check to see if the string being replaced is part of the replacement string or not
	   return temp; // Send the updated string back to the user
	} // Ends the "replaceSubstring" function
	
}
function checkField(Fieldname, FriendlyName, maxRows, maxChars, Required)
{
	this.Fieldname = Fieldname;
	this.FriendlyName = FriendlyName;
	this.maxRows = maxRows;
	this.maxChars = maxChars;
	this.Required = Required;
	this.isMail = false;
	this.isPostalCode = false;
	this.isPercentage = false;
	this.minPercentage = 0;
	this.maxPercentage = 100;
	this.isNumeric = false;
}
function checkFileField(Fieldname, FriendlyName, Extensions, Required)
{
	this.Fieldname = Fieldname;
	this.FriendlyName = FriendlyName;	
	this.ExtensionsTXT = Extensions;
	this.Extensions = Extensions.split(",");
	this.Required = Required;
}