// If the length of the element's string is 0 then display helper message
function isEmpty(elem, helperMsg){
	if(elem.value.length == 0){
		alert(helperMsg);
		elem.focus(); // set the focus to this input
		return true;
	}
	return false;
}


// If the element's string matches the regular expression it is all numbers and, optionally, whitespace
function isNumeric(elem, helperMsg, allowWhiteSpace){
	if (allowWhiteSpace) {
		var numericExpression = /^[0-9\s]+$/;
	} else {
		var numericExpression = /^[0-9]+$/;
	}
	if(elem.value.match(numericExpression)){
		return true;
	}else{
		alert(helperMsg);
		elem.focus();
		return false;
	}
}


// If element's string matched the regular expression it is a valid money format
function isMoney(elem, helperMsg) {
	var monExpr=/^(\d{0,4})(\.?)(\d{0,2})$/;
	if (elem.value.match(monExpr)) {
		return true;
	} else {
		alert(helperMsg);
		elem.focus();
		return false;
	}
}


// If element's string matched the regular expression it is a valid decimal number
function isDecimal(elem, helperMsg) {
	var decExpr=/^(-)?(\d*)(\.?)(\d*)$/;
	if (elem.value.match(decExpr)) {
		return true;
	} else {
		alert(helperMsg);
		elem.focus();
		return false;
	}
}


// If the element's string matches the regular expression it is all letters and, optionally, whitespace
function isAlphabet(elem, helperMsg, allowWhiteSpace){
	if (allowWhiteSpace) {
		var alphaExp = /^[a-zA-Z\s]+$/;
	} else {
		var alphaExp = /^[a-zA-Z]+$/;
	}
	if(elem.value.match(alphaExp)){
		return true;
	}else{
		alert(helperMsg);
		elem.focus();
		return false;
	}
}


// If the element's string matches the regular expression it is numbers and letters and, optionally, whitespace
function isAlphanumeric(elem, helperMsg, allowWhiteSpace){
	if (allowWhiteSpace) {
		var alphaExp = /^[0-9a-zA-Z\s]+$/;
	} else {
		var alphaExp = /^[0-9a-zA-Z]+$/;
	}
	if(elem.value.match(alphaExp)){
		return true;
	}else{
		alert(helperMsg);
		elem.focus();
		return false;
	}
}


function lengthRestriction(elem, min, max){
	var uInput = elem.value;
	if(uInput.length >= min && uInput.length <= max){
		return true;
	}else{
		alert("Please enter between " +min+ " and " +max+ " characters");
		elem.select();
		return false;
	}
}


function emailValidator(elem, helperMsg){
	var emailExp = /^[\w\-\.\+]+\@[a-zA-Z0-9\.\-]+\.[a-zA-z0-9]{2,4}$/;
	if(elem.value.match(emailExp)){
		return true;
	}else{
		alert(helperMsg);
		elem.focus();
		return false;
	}
}


function checkPassWords(elem1, elem2, helperMsg) {
	if (elem1.value == elem2.value) {
		return true;
	} else {
		alert(helperMsg);
		elem1.value="";
		elem2.value="";
		elem1.focus();
		return false;
	}
}

function checkPasswordText(elem, helperMsg) {
	if ((elem.value.indexOf(";") == -1) && (elem.value.indexOf("'") == -1) && (elem.value.indexOf("1=1") == -1) && (elem.value.indexOf('"') == -1) && (elem.value.indexOf("\\") == -1) && (elem.value.indexOf("/") == -1)) {
		return true;
	} else {
		alert(helperMsg);
		elem.value="";
		elem.focus();
		return false;
	}
}

function checkAge(elem, helperMsg) {
	if (elem.checked==true) {
		return true;
	} else {
		alert(helperMsg);
		elem.focus();
		return false;
	}
}

function checkNotZero(elem, helperMsg) {
	if (elem.value>0) {
		return true;
	} else {
		alert(helperMsg);
		elem.focus();
		return false;
	}
}

function isChecked(elem, helperMsg) {
	if (elem.checked) {
		return true;
	} else {
		alert(helperMsg);
		elem.focus();
		return false;
	}
}

function isPostcode(elem, helperMsg) {
	if (checkPostCode(elem.value)) {
		return true;
	} else {
		alert(helperMsg);
		elem.focus();
		return false;
	}
}

function checkPostCode (toCheck) {
	// function from John Gardner (http://www.braemoor.co.uk/software/postcodes.shtml

	// Permitted letters depend upon their position in the postcode.
	var alpha1 = "[abcdefghijklmnoprstuwyz]";                       // Character 1
	var alpha2 = "[abcdefghklmnopqrstuvwxy]";                       // Character 2
	var alpha3 = "[abcdefghjkstuw]";                                // Character 3
	var alpha4 = "[abehmnprvwxy]";                                  // Character 4
	var alpha5 = "[abdefghjlnpqrstuwxyz]";                          // Character 5


	// Array holds the regular expressions for the valid postcodes
	var pcexp = new Array ();

	// Expression for postcodes: AN NAA, ANN NAA, AAN NAA, and AANN NAA
	pcexp.push (new RegExp ("^(" + alpha1 + "{1}" + alpha2 + "?[0-9]{1,2})(\\s*)([0-9]{1}" + alpha5 + "{2})$","i"));

	// Expression for postcodes: ANA NAA
	pcexp.push (new RegExp ("^(" + alpha1 + "{1}[0-9]{1}" + alpha3 + "{1})(\\s*)([0-9]{1}" + alpha5 + "{2})$","i"));

	// Expression for postcodes: AANA  NAA
	pcexp.push (new RegExp ("^(" + alpha1 + "{1}" + alpha2 + "?[0-9]{1}" + alpha4 +"{1})(\\s*)([0-9]{1}" + alpha5 + "{2})$","i"));

	// Exception for the special postcode GIR 0AA
	pcexp.push (/^(GIR)(\s*)(0AA)$/i);

	// Standard BFPO numbers
	pcexp.push (/^(bfpo)(\s*)([0-9]{1,4})$/i);

	// c/o BFPO numbers
	pcexp.push (/^(bfpo)(\s*)(c\/o\s*[0-9]{1,3})$/i);

	// Load up the string to check
	var postCode = toCheck;

	// Assume we're not going to find a valid postcode
	var valid = false;

	// Check the string against the types of post codes
	for ( var i=0; i<pcexp.length; i++) {
		if (pcexp[i].test(postCode)) {

			// The post code is valid - split the post code into component parts
			pcexp[i].exec(postCode);

			// Copy it back into the original string, converting it to uppercase and
			// inserting a space between the inward and outward codes
			postCode = RegExp.$1.toUpperCase() + " " + RegExp.$3.toUpperCase();

			// If it is a BFPO c/o type postcode, tidy up the "c/o" part
			postCode = postCode.replace (/C\/O\s*/,"c/o ");

			// Load new postcode back into the form element
			valid = true;

			// Remember that we have found that the code is valid and break from loop
			break;
		}
	}

	// Return with either the reformatted valid postcode or the original invalid 
	// postcode
	if (valid) {return postCode;} else return false;
}