// 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;
}