function IsNumeric(sText) {
   var ValidChars = "0123456789.";
   var IsNumber=true;
   var Char;
 
   for (i = 0; i < sText.length && IsNumber == true; i++) { 
      Char = sText.charAt(i); 
      if (ValidChars.indexOf(Char) == -1) {
         IsNumber = false;
      }
   }
   return IsNumber;
}

function IsEmpty(aTextField) {
   if ((aTextField.value.length==0) ||
   (aTextField.value==null)) {
      return true;
   }
   else { return false; }
}

function isEmail(str) {
  // are regular expressions supported?
  var supported = 0;
  if (window.RegExp) {
    var tempStr = "a";
    var tempReg = new RegExp(tempStr);
    if (tempReg.test(tempStr)) supported = 1;
  }
  if (!supported) 
    return (str.indexOf(".") > 2) && (str.indexOf("@") > 0);
  var r1 = new RegExp("(@.*@)|(\\.\\.)|(@\\.)|(^\\.)");
  var r2 = new RegExp("^.+\\@(\\[?)[a-zA-Z0-9\\-\\.]+\\.([a-zA-Z]{2,3}|[0-9]{1,3})(\\]?)$");
  return (!r1.test(str) && r2.test(str));
}

function ValidateForm(form) {
   if(IsEmpty(form.name)) { 
      alert('You forgot to enter your name') 
      form.name.focus(); 
      return false; 
   } 

   if(IsEmpty(form.address)) {
      alert('You forgot to enter your address') 
      form.address.focus(); 
      return false; 
   } 

   if(IsEmpty(form.postcode)) {
      alert('You forgot to enter your postcode') 
      form.postcode.focus();
      return false; 
   } 

   if(!(isEmail(form.email.value))) { 
      alert('Please enter valid email address.')
      form.email.focus(); 
      return false; 
   } 


   if(IsEmpty(form.enquiry)) {
      alert('You forgot to enter enquiry or comment') 
      form.enquiry.focus();
      return false; 
   } 

 
   return true;
}