<!--form validation functions-->
 function IsEmpty(aTextField) {
   if ((aTextField.length==0) ||
   (aTextField==null)) {
      return true;
   }
   else { return false; }
}

function isValidEmail(str) {
   return (str.indexOf(".") > 0) && (str.indexOf("@") > 0);
 
}

function IsAlpha(aText)
{
   var aValidChars = "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz ";
   var IsAlpha=true;
   var Char;

 
   for (a = 0; a < aText.length && IsAlpha == true; a++) 
      { 
      Char = aText.charAt(a); 
      if (aValidChars.indexOf(Char) == -1) 
         {
         IsAlpha = false;
         }
      }
   return IsAlpha;
   
   }
   
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 IsCCNum(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;
         }
		if(sText.length != 16)
		{
			IsNumber = false;
		}
      }
   return IsNumber;
   
   }
   
   function IsZip(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;
         }
		if(sText.length != 5)
		{
			IsNumber = false;
		}
      }
   return IsNumber;
   
   }
   
   function IsPhone(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;
         }
		if(sText.length != 10)
		{
			IsNumber = false;
		}
      }
   return IsNumber;
   
   }
function validateForm(){
	if (IsEmpty(document.billingForm.ssl_first_name.value)){
		alert("Please Add First Name");
		document.billingForm.ssl_first_name.focus();
	}
	else if (IsEmpty(document.billingForm.ssl_last_name.value)){
		alert("Please Add Last Name");
		document.billingForm.ssl_last_name.focus();
	}
	else if (IsEmpty(document.billingForm.ssl_avs_address.value)){
		alert("Please Add Address");
		document.billingForm.ssl_avs_address.focus();
	}
	else if (!IsAlpha(document.billingForm.ssl_city.value) || IsEmpty(document.billingForm.ssl_city.value)){
		alert("Please City");
		document.billingForm.ssl_city.focus();
	}
	else if (!IsAlpha(document.billingForm.ssl_state.value) || IsEmpty(document.billingForm.ssl_state.value)){
		alert("Please Add State");
		document.billingForm.ssl_state.focus();
	}
	else if (!IsZip(document.billingForm.ssl_avs_zip.value) || IsEmpty(document.billingForm.ssl_avs_zip.value)){
		alert("Zip Code is missing or invalid");
		document.billingForm.ssl_avs_zip.focus();
	}
	else if (!IsPhone(document.billingForm.ssl_phone.value) || IsEmpty(document.billingForm.ssl_phone.value)){
		alert("Phone number is missing or invalid. Please enter your 10 digit phone number");
		document.billingForm.ssl_phone.focus();
	}
	else if (!isValidEmail(document.billingForm.ssl_email.value)){
		alert("Email address is invalid");
		document.billingForm.ssl_email.focus();
	}
	else if (document.billingForm.ccType.value == '0'){
		alert("Please Select a Card Type");
		document.billingForm.ccType.focus();
	}
	else if (!IsCCNum(document.billingForm.ssl_card_number.value) || IsEmpty(document.billingForm.ssl_card_number.value)){
		alert("Credit/Debit Card Number is missing or invalid");
		document.billingForm.ssl_card_number.focus();
	}
	else if (!IsNumeric(document.billingForm.ssl_exp_date.value) || IsEmpty(document.billingForm.ssl_exp_date.value)){
		alert("Credit/Debit Card Exp. date is missing or invalid");
		document.billingForm.ssl_exp_date.focus();
	}
	else {
		document.billingForm.submit();
	}

}
<!--end form validation functions-->