function trimXS(strXS){
	while(strXS.charAt(0)==(" ")){strXS=strXS.substring(1)}
  while(strXS.charAt(strXS.length-1)==" "){strXS=strXS.substring(0,strXS.length-1)}
  return strXS;
}

function resetStyles() {
	document.Form1.name.className           ="xprequired";
	document.Form1.sender_address.className ="xprequired";
	document.Form1.postcode.className       ="xpinput";
	document.Form1.telephone.className      ="xpinput";
}

function checkForm() {
/* define regular expression test patterns */
	testEmail           = /^([0-9a-zA-Z]([-.\w]*[0-9a-zA-Z])*@([0-9a-zA-Z][-\w][^_]*[0-9a-zA-Z]\.)+[a-zA-Z]{2,9})$/;
	testPostcodeUK      = /^([A-PR-UWYZ0-9][A-HK-Y0-9][ABCDEFGHJKSTUW0-9]?[ABEHMNPRVWXY0-9]? {1,2}[0-9][ABD-HJLNP-UW-Z]{2}|GIR 0AA)$/;
	testPostcodeForeign = /^[X][A-Z][A-Z]\ [0-9A-Z -]+$/;
	testTelephone       = /[A-Za-z_.@'!"£$%^&*()-]/; // "

/* form element names */
	optName       = document.Form1.name;
	optEmail      = document.Form1.sender_address;
	optAddress    = document.Form1.address;
	optPostcode   = document.Form1.postcode;
	optTelephone  = document.Form1.telephone;
	optComments   = document.Form1.comments;
	optTransactionDate   = document.Form1.transaction_date;
	optTransactionReference   = document.Form1.transaction_reference;
	optProductDescription   = document.Form1.product_description;

/* reset warning styles */
	resetStyles();

/* form element values */
	optName.value                 = trimXS(optName.value);      strName      = optName.value;
	optEmail.value                = trimXS(optEmail.value);     strEmail     = optEmail.value;
	optAddress.value              = trimXS(optAddress.value); // not validated
	optPostcode.value             = trimXS(optPostcode.value);  strPostcode  = optPostcode.value.toUpperCase();
	optTelephone.value            = trimXS(optTelephone.value); strTelephone = optTelephone.value;
	optComments.value             = trimXS(optComments.value); // not validated
	optTransactionDate.value      = trimXS(optTransactionDate.value); // not validated
	optTransactionReference.value = trimXS(optTransactionReference.value); // not validated
	optProductDescription.value   = trimXS(optProductDescription.value); // not validated

/* check whether to use UK or foreign test pattern */
	var pcValid = testPostcodeUK;
	var pcTest  = strPostcode.charAt(0);
	if (pcTest=="X") { pcValid = testPostcodeForeign }

/* replace hyphens in telephone numbers with white space */
	while (strTelephone.search("-") > -1) { strTelephone = strTelephone.replace("-"," ") }
	document.Form1.telephone.value = strTelephone;

/* define alert messages */
	var msg = "", Flag = 0, FlagName = 0, FlagPostcode = 0, FlagTelephone = 0, FlagEmail = 0;
	var msgFill      = "\n- - - - - - - - - - - - - - - - - - - - - - - - - -\n";

	var msgName      = "Please enter your Name\n";
	var msgEmailA    = "Please enter your Email Address\n";
	var msgEmailB    = "Sorry, but \"" + strEmail + "\" is an invalid Email Address\n";
	var msgPostcode  = "Sorry, but \"" + strPostcode + "\" is an invalid Postcode,\nor you have omitted the central space\n";
	var msgTelephone = "Sorry, but \"" + strTelephone + "\" is an invalid telephone number\n";

/* step through each validation check and assemble Alert Message */
	if (strName == "") {
		FlagName = 1;
		Flag = 1;
		msg = msg + msgFill + msgName;
		optName.className="badValue";
	}

	if (strEmail == "") {
		FlagEmail = 1;
		Flag = 2;
		if(FlagName) { Flag = 1 }
		msg = msg + msgFill + msgEmailA;
		optEmail.className="badValue";
	}

	if ((strEmail != "") && (! testEmail.test(strEmail))) {
		FlagEmail = 1;
		Flag = 2;
		if(FlagName) { Flag = 1 }
		msg = msg + msgFill + msgEmailB;
		optEmail.className="badValue";
	}

	if ((strPostcode != "") && (! pcValid.test(strPostcode))) {
		FlagPostcode = 1;
		Flag = 3;
		if(FlagEmail) { Flag = 2 }
		if(FlagName) { Flag = 1 }
		msg = msg + msgFill + msgPostcode;
		optPostcode.className="badValue";
	}

	if ((strTelephone != "") && (testTelephone.test(strTelephone))) {
		FlagTelephone = 1;
		Flag = 4;
		if(FlagPostcode) { Flag = 3 }
		if(FlagEmail) { Flag = 2 }
		if(FlagName) { Flag = 1 }
		msg = msg + msgFill + msgTelephone;
		optTelephone.className="badValue";
	}

/* determine which box to set focus on and display Alert */	
	if (Flag >=1 ) {
		if (Flag == 1) {optName.focus();}
		if (Flag == 2) {optEmail.focus();}
		if (Flag == 3) {optPostcode.focus();}
		if (Flag == 4) {optTelephone.focus();}

		alert(msg);
	}

	else if(document.Form1.mstp.value != ""){
		location.href="Contact.asp?rp=1";
	}
	
	else {
		document.Form1.Referrer_Site.value = referrerSite;
		document.Form1.submit();
//alert("passed OK");
	}
}