// FormChek.js

//

// SUMMARY

//

// This is a set of JavaScript functions for validating input on 

// an HTML form.  Functions are provided to validate:

//

//      - U.S. and international phone/fax numbers

//      - U.S. ZIP codes (5 or 9 digit postal codes)

//      - U.S. Postal Codes (2 letter abbreviations for names of states)

//      - U.S. Social Security Numbers (abbreviated as SSNs)

//      - email addresses

//      - dates (entry of year, month, and day and validity of combined date)

//      - credit card numbers

//

// Supporting utility functions validate that:

//

//      - characters are Letter, Digit, or LetterOrDigit

//      - strings are a Signed, Positive, Negative, Nonpositive, or

//        Nonnegative integer

//      - strings are a Float or a SignedFloat

//      - strings are Alphabetic, Alphanumeric, or Whitespace

//      - strings contain an integer within a specified range

//

// Functions are also provided to interactively check the

// above kinds of data and prompt the user if they have

// been entered incorrectly.

//

// Other utility functions are provided to:

//

//      - remove from a string characters which are/are not 

//        in a "bag" of selected characters     

//      - reformat a string, adding delimiter characters

//      - strip whitespace/leading whitespace from a string

//      - reformat U.S. phone numbers, ZIP codes, and Social

//        Security numbers

//

//

// Many of the below functions take an optional parameter eok (for "emptyOK")

// which determines whether the empty string will return true or false.

// Default behavior is controlled by global variable defaultEmptyOK.

//

// BASIC DATA VALIDATION FUNCTIONS:

//

// isWhitespace (s)                    Check whether string s is empty or whitespace.

// isLetter (c)                        Check whether character c is an English letter 

// isDigit (c)                         Check whether character c is a digit 

// isLetterOrDigit (c)                 Check whether character c is a letter or digit.

// isInteger (s [,eok])                True if all characters in string s are numbers.

// isSignedInteger (s [,eok])          True if all characters in string s are numbers; leading + or - allowed.

// isPositiveInteger (s [,eok])        True if string s is an integer > 0.

// isNonnegativeInteger (s [,eok])     True if string s is an integer >= 0.

// isNegativeInteger (s [,eok])        True if s is an integer < 0.

// isNonpositiveInteger (s [,eok])     True if s is an integer <= 0.

// isFloat (s [,eok])                  True if string s is an unsigned floating point (real) number. (Integers also OK.)

// isSignedFloat (s [,eok])            True if string s is a floating point number; leading + or - allowed. (Integers also OK.)

// isAlphabetic (s [,eok])             True if string s is English letters 

// isAlphanumeric (s [,eok])           True if string s is English letters and numbers only.

// 

// isSSN (s [,eok])                    True if string s is a valid U.S. Social Security Number.

// isUSPhoneNumber (s [,eok])          True if string s is a valid U.S. Phone Number. 

// isInternationalPhoneNumber (s [,eok]) True if string s is a valid international phone number.

// isZIPCode (s [,eok])                True if string s is a valid U.S. ZIP code.

// isStateCode (s [,eok])              True if string s is a valid U.S. Postal Code

// isEmail (s [,eok])                  True if string s is a valid email address.

// isYear (s [,eok])                   True if string s is a valid Year number.

// isIntegerInRange (s, a, b [,eok])   True if string s is an integer between a and b, inclusive.

// isMonth (s [,eok])                  True if string s is a valid month between 1 and 12.

// isDay (s [,eok])                    True if string s is a valid day between 1 and 31.

// daysInFebruary (year)               Returns number of days in February of that year.

// isDate (year, month, day)           True if string arguments form a valid date.





// FUNCTIONS TO REFORMAT DATA:

//

// stripCharsInBag (s, bag)            Removes all characters in string bag from string s.

// stripCharsNotInBag (s, bag)         Removes all characters NOT in string bag from string s.

// stripWhitespace (s)                 Removes all whitespace characters from s.

// stripInitialWhitespace (s)          Removes initial (leading) whitespace characters from s.

// reformat (TARGETSTRING, STRING,     Function for inserting formatting characters or

//   INTEGER, STRING, INTEGER ... )       delimiters into TARGETSTRING.                                       

// reformatZIPCode (ZIPString)         If 9 digits, inserts separator hyphen.

// reformatSSN (SSN)                   Reformats as 123-45-6789.

// reformatUSPhone (USPhone)           Reformats as (123) 456-789.





// FUNCTIONS TO PROMPT USER:

//

// prompt (s)                          Display prompt string s in status bar.

// promptEntry (s)                     Display data entry prompt string s in status bar.

// warnEmpty (theField, s)             Notify user that required field theField is empty.

// warnInvalid (theField, s)           Notify user that contents of field theField are invalid.





// FUNCTIONS TO INTERACTIVELY CHECK FIELD CONTENTS:

//

// checkString (theField, s [,eok])    Check that theField.value is not empty or all whitespace.

// checkStateCode (theField)           Check that theField.value is a valid U.S. state code.

// checkZIPCode (theField [,eok])      Check that theField.value is a valid ZIP code.

// checkUSPhone (theField [,eok])      Check that theField.value is a valid US Phone.

// checkInternationalPhone (theField [,eok])  Check that theField.value is a valid International Phone.

// checkEmail (theField [,eok])        Check that theField.value is a valid Email.

// checkSSN (theField [,eok])          Check that theField.value is a valid SSN.

// checkYear (theField [,eok])         Check that theField.value is a valid Year.

// checkMonth (theField [,eok])        Check that theField.value is a valid Month.

// checkDay (theField [,eok])          Check that theField.value is a valid Day.

// checkDate (yearField, monthField, dayField, labelString, OKtoOmitDay)

//                                     Check that field values form a valid date.

// getRadioButtonValue (radio)         Get checked value from radio button.

// checkCreditCard (radio, theField)   Validate credit card info.





// VARIABLE DECLARATIONS



var digits = "0123456789";



var lowercaseLetters = "abcdefghijklmnopqrstuvwxyz"



var uppercaseLetters = "ABCDEFGHIJKLMNOPQRSTUVWXYZ"





// whitespace characters

var whitespace = " \t\n\r";





// decimal point character differs by language and culture

var decimalPointDelimiter = "."





// non-digit characters which are allowed in phone numbers

var phoneNumberDelimiters = "()-+ ";





// characters which are allowed in US phone numbers

var validUSPhoneChars = digits + phoneNumberDelimiters;





// characters which are allowed in international phone numbers

// (a leading + is OK)

var validWorldPhoneChars = digits + phoneNumberDelimiters + "+";





// non-digit characters which are allowed in 

// Social Security Numbers

var SSNDelimiters = "- ";







// characters which are allowed in Social Security Numbers

var validSSNChars = digits + SSNDelimiters;











// U.S. Social Security Numbers have 9 digits.

// They are formatted as 123-45-6789.

var digitsInSocialSecurityNumber = 9;







// U.S. phone numbers have 10 digits.

// They are formatted as 123 456 7890 or (123) 456-7890.

var digitsInUSPhoneNumber = 10;







// non-digit characters which are allowed in ZIP Codes

var ZIPCodeDelimiters = "-";







// our preferred delimiter for reformatting ZIP Codes

var ZIPCodeDelimeter = "-"





// characters which are allowed in Social Security Numbers

var validZIPCodeChars = digits + ZIPCodeDelimiters







// U.S. ZIP codes have 5 or 9 digits.

// They are formatted as 12345 or 12345-6789.

var digitsInZIPCode1 = 5

var digitsInZIPCode2 = 9





// non-digit characters which are allowed in credit card numbers

var creditCardDelimiters = " "





// CONSTANT STRING DECLARATIONS

// (grouped for ease of translation and localization)



// m is an abbreviation for "missing"



var mPrefix = "You did not enter a value into the "

var mSuffix = " field. This is a required field. Please enter it now."



// s is an abbreviation for "string"



var sUSLastName = "Last Name"

var sUSFirstName = "First Name"

var sWorldLastName = "Family Name"

var sWorldFirstName = "Name"

var sWorldLoginId = "Given Login ID"

var sWorldPassword = "Given Password"

var sWorldContactPerson = "Given Contact Person Name"

var sDesignation ="Given Designation"

var sTitle = "Title"

var sCompanyName = "Company Name"

var sInstituteName = "Institute Name"

var sUSAddress = "Street Address"

var sWorldAddress = "Address"

var sCity = "City"

var sStateCode = "State Code"

var sWorldState = "State, Province, or Prefecture"

var sCountry = "Country"

var sZIPCode = "ZIP Code"

var sWorldPostalCode = "Postal Code"

var sPhone = "Phone Number"

var sFax = "Fax Number"

var sDateOfBirth = "Date of Birth"

var sExpirationDate = "Expiration Date"

var sEmail = "Email"

var sSSN = "Social Security Number"

var sCreditCardNumber = "Credit Card Number"

var sOtherInfo = "Other Information"

var sFuntionalInfo = "Funtional Area of Interest"

var sPositionVacant = "Position Vacant"

var sBrifeofJob = "Brief Description of job"

var sEssSkil = "Essential Skill"

var sResPone = "Responsibility"

var sPostedby = "Posted By"

var sLoginid = "User Name"

var sPassword = "Password"

var sKeywd = "Key Word for Skill Set"

var sCompanyName = "Company Name"











// i is an abbreviation for "invalid"



var iStateCode = "This field must be a valid two character U.S. state abbreviation (like CA for California). Please reenter it now."

var iZIPCode = "This field must be a 5 or 9 digit U.S. ZIP Code (like 94043). Please reenter it now."

var iUSPhone = "This field must be a 10 digit U.S. phone number (like 415 555 1212). Please reenter it now."

var iWorldPhone = "This field must be a valid international phone number. Please reenter it now."

var iSSN = "This field must be a 9 digit U.S. social security number (like 123 45 6789). Please reenter it now."

var iEmail = "This field must be a valid email address (user@host.domain). Please reenter it now."

var iCreditCardPrefix = "This is not a valid "

var iCreditCardSuffix = " credit card number. (Click the link on this form to see a list of sample numbers.) Please reenter it now."

var iDay = "This field must be a day number between 1 and 31.  Please reenter it now."

var iMonth = "This field must be a month number between 1 and 12.  Please reenter it now."

var iYear = "This field must be a 4 digit year number.  Please reenter it now."

var iDatePrefix = "The Day, Month, and Year for "

var iDateSuffix = " do not form a valid date.  Please reenter them now."







// p is an abbreviation for "prompt"



var pEntryPrompt = "Please enter a "

var pStateCode = "2 character code (like CA)."

var pZIPCode = "5 or 9 digit U.S. ZIP Code (like 94043)."

var pUSPhone = "10 digit U.S. phone number (like 415 555 1212)."

var pWorldPhone = "international phone number."

var pSSN = "9 digit U.S. social security number (like 123 45 6789)."

var pEmail = "valid email address (like foo@bar.com)."

var pCreditCard = "valid credit card number."

var pDay = "day number between 1 and 31."

var pMonth = "month number between 1 and 12."

var pYear = "2 or 4 digit year number."





// Global variable defaultEmptyOK defines default return value 

// for many functions when they are passed the empty string. 

// By default, they will return defaultEmptyOK.

//

// defaultEmptyOK is false, which means that by default, 

// these functions will do "strict" validation.  Function

// isInteger, for example, will only return true if it is

// passed a string containing an integer; if it is passed

// the empty string, it will return false.

//

// You can change this default behavior globally (for all 

// functions which use defaultEmptyOK) by changing the value

// of defaultEmptyOK.

//

// Most of these functions have an optional argument emptyOK

// which allows you to override the default behavior for 

// the duration of a function call.

//

// This functionality is useful because it is possible to

// say "if the user puts anything in this field, it must

// be an integer (or a phone number, or a string, etc.), 

// but it's OK to leave the field empty too."

// This is the case for fields which are optional but which

// must have a certain kind of content if filled in.



var defaultEmptyOK = false









// Attempting to make this library run on Navigator 2.0,

// so I'm supplying this array creation routine as per

// JavaScript 1.0 documentation.  If you're using 

// Navigator 3.0 or later, you don't need to do this;

// you can use the Array constructor instead.



function makeArray(n) {

//*** BUG: If I put this line in, I get two error messages:

//(1) Window.length can't be set by assignment

//(2) daysInMonth has no property indexed by 4

//If I leave it out, the code works fine.

//   this.length = n;

   for (var i = 1; i <= n; i++) {

      this[i] = 0

   } 

   return this

}







var daysInMonth = makeArray(12);

daysInMonth[1] = 31;

daysInMonth[2] = 29;   // must programmatically check this

daysInMonth[3] = 31;

daysInMonth[4] = 30;

daysInMonth[5] = 31;

daysInMonth[6] = 30;

daysInMonth[7] = 31;

daysInMonth[8] = 31;

daysInMonth[9] = 30;

daysInMonth[10] = 31;

daysInMonth[11] = 30;

daysInMonth[12] = 31;









// Valid U.S. Postal Codes for states, territories, armed forces, etc.

// See http://www.usps.gov/ncsc/lookups/abbr_state.txt.



var USStateCodeDelimiter = "|";

var USStateCodes = "AL|AK|AS|AZ|AR|CA|CO|CT|DE|DC|FM|FL|GA|GU|HI|ID|IL|IN|IA|KS|KY|LA|ME|MH|MD|MA|MI|MN|MS|MO|MT|NE|NV|NH|NJ|NM|NY|NC|ND|MP|OH|OK|OR|PW|PA|PR|RI|SC|SD|TN|TX|UT|VT|VI|VA|WA|WV|WI|WY|AE|AA|AE|AE|AP"









// Check whether string s is empty.



function isEmpty(s)

{   return ((s == null) || (s.length == 0))

}







// Returns true if string s is empty or 

// whitespace characters only.



function isWhitespace (s)



{   var i;



    // Is s empty?

    if (isEmpty(s)) return true;



    // Search through string's characters one by one

    // until we find a non-whitespace character.

    // When we do, return false; if we don't, return true.



    for (i = 0; i < s.length; i++)

    {   

        // Check that current character isn't whitespace.

        var c = s.charAt(i);



        if (whitespace.indexOf(c) == -1) return false;

    }



    // All characters are whitespace.

    return true;

}







// Removes all characters which appear in string bag from string s.



function stripCharsInBag (s, bag)



{   var i;

    var returnString = "";



    // Search through string's characters one by one.

    // If character is not in bag, append to returnString.



    for (i = 0; i < s.length; i++)

    {   

        // Check that current character isn't whitespace.

        var c = s.charAt(i);

        if (bag.indexOf(c) == -1) returnString += c;

    }



    return returnString;

}







// Removes all characters which do NOT appear in string bag 

// from string s.



function stripCharsNotInBag (s, bag)



{   var i;

    var returnString = "";



    // Search through string's characters one by one.

    // If character is in bag, append to returnString.



    for (i = 0; i < s.length; i++)

    {   

        // Check that current character isn't whitespace.

        var c = s.charAt(i);

        if (bag.indexOf(c) != -1) returnString += c;

    }



    return returnString;

}







// Removes all whitespace characters from s.

// Global variable whitespace (see above)

// defines which characters are considered whitespace.



function stripWhitespace (s)



{   return stripCharsInBag (s, whitespace)

}









// WORKAROUND FUNCTION FOR NAVIGATOR 2.0.2 COMPATIBILITY.

//

// The below function *should* be unnecessary.  In general,

// avoid using it.  Use the standard method indexOf instead.

//

// However, because of an apparent bug in indexOf on 

// Navigator 2.0.2, the below loop does not work as the

// body of stripInitialWhitespace:

//

// while ((i < s.length) && (whitespace.indexOf(s.charAt(i)) != -1))

//   i++;

//

// ... so we provide this workaround function charInString

// instead.

//

// charInString (CHARACTER c, STRING s)

//

// Returns true if single character c (actually a string)

// is contained within string s.



function charInString (c, s)

{   for (i = 0; i < s.length; i++)

    {   if (s.charAt(i) == c) return true;

    }

    return false

}







// Removes initial (leading) whitespace characters from s.

// Global variable whitespace (see above)

// defines which characters are considered whitespace.



function stripInitialWhitespace (s)



{   var i = 0;



    while ((i < s.length) && charInString (s.charAt(i), whitespace))

       i++;

    

    return s.substring (i, s.length);

}















// Returns true if character c is an English letter 

// (A .. Z, a..z).

//

// NOTE: Need i18n version to support European characters.

// This could be tricky due to different character

// sets and orderings for various languages and platforms.



function isLetter (c)

{   return ( ((c >= "a") && (c <= "z")) || ((c >= "A") && (c <= "Z")) )

}







// Returns true if character c is a digit 

// (0 .. 9).



function isDigit (c)

{   return ((c >= "0") && (c <= "9"))

}







// Returns true if character c is a letter or digit.



function isLetterOrDigit (c)

{   return (isLetter(c) || isDigit(c))

}







// isInteger (STRING s [, BOOLEAN emptyOK])

// 

// Returns true if all characters in string s are numbers.

//

// Accepts non-signed integers only. Does not accept floating 

// point, exponential notation, etc.

//

// We don't use parseInt because that would accept a string

// with trailing non-numeric characters.

//

// By default, returns defaultEmptyOK if s is empty.

// There is an optional second argument called emptyOK.

// emptyOK is used to override for a single function call

//      the default behavior which is specified globally by

//      defaultEmptyOK.

// If emptyOK is false (or any value other than true), 

//      the function will return false if s is empty.

// If emptyOK is true, the function will return true if s is empty.

//

// EXAMPLE FUNCTION CALL:     RESULT:

// isInteger ("5")            true 

// isInteger ("")             defaultEmptyOK

// isInteger ("-5")           false

// isInteger ("", true)       true

// isInteger ("", false)      false

// isInteger ("5", false)     true



function isInteger (s)



{   var i;



    if (isEmpty(s)) 

       if (isInteger.arguments.length == 1) return defaultEmptyOK;

       else return (isInteger.arguments[1] == true);



    // Search through string's characters one by one

    // until we find a non-numeric character.

    // When we do, return false; if we don't, return true.



    for (i = 0; i < s.length; i++)

    {   

        // Check that current character is number.

        var c = s.charAt(i);



        if (!isDigit(c)) return false;

    }



    // All characters are numbers.

    return true;

}















// isSignedInteger (STRING s [, BOOLEAN emptyOK])

// 

// Returns true if all characters are numbers; 

// first character is allowed to be + or - as well.

//

// Does not accept floating point, exponential notation, etc.

//

// We don't use parseInt because that would accept a string

// with trailing non-numeric characters.

//

// For explanation of optional argument emptyOK,

// see comments of function isInteger.

//

// EXAMPLE FUNCTION CALL:          RESULT:

// isSignedInteger ("5")           true 

// isSignedInteger ("")            defaultEmptyOK

// isSignedInteger ("-5")          true

// isSignedInteger ("+5")          true

// isSignedInteger ("", false)     false

// isSignedInteger ("", true)      true



function isSignedInteger (s)



{   if (isEmpty(s)) 

       if (isSignedInteger.arguments.length == 1) return defaultEmptyOK;

       else return (isSignedInteger.arguments[1] == true);



    else {

        var startPos = 0;

        var secondArg = defaultEmptyOK;



        if (isSignedInteger.arguments.length > 1)

            secondArg = isSignedInteger.arguments[1];



        // skip leading + or -

        if ( (s.charAt(0) == "-") || (s.charAt(0) == "+") )

           startPos = 1;    

        return (isInteger(s.substring(startPos, s.length), secondArg))

    }

}









// isPositiveInteger (STRING s [, BOOLEAN emptyOK])

// 

// Returns true if string s is an integer > 0.

//

// For explanation of optional argument emptyOK,

// see comments of function isInteger.



function isPositiveInteger (s)

{   var secondArg = defaultEmptyOK;



    if (isPositiveInteger.arguments.length > 1)

        secondArg = isPositiveInteger.arguments[1];



    // The next line is a bit byzantine.  What it means is:

    // a) s must be a signed integer, AND

    // b) one of the following must be true:

    //    i)  s is empty and we are supposed to return true for

    //        empty strings

    //    ii) this is a positive, not negative, number



    return (isSignedInteger(s, secondArg)

         && ( (isEmpty(s) && secondArg)  || (parseInt (s) > 0) ) );

}













// isNonnegativeInteger (STRING s [, BOOLEAN emptyOK])

// 

// Returns true if string s is an integer >= 0.

//

// For explanation of optional argument emptyOK,

// see comments of function isInteger.



function isNonnegativeInteger (s)

{   var secondArg = defaultEmptyOK;



    if (isNonnegativeInteger.arguments.length > 1)

        secondArg = isNonnegativeInteger.arguments[1];



    // The next line is a bit byzantine.  What it means is:

    // a) s must be a signed integer, AND

    // b) one of the following must be true:

    //    i)  s is empty and we are supposed to return true for

    //        empty strings

    //    ii) this is a number >= 0



    return (isSignedInteger(s, secondArg)

         && ( (isEmpty(s) && secondArg)  || (parseInt (s) >= 0) ) );

}













// isNegativeInteger (STRING s [, BOOLEAN emptyOK])

// 

// Returns true if string s is an integer < 0.

//

// For explanation of optional argument emptyOK,

// see comments of function isInteger.



function isNegativeInteger (s)

{   var secondArg = defaultEmptyOK;



    if (isNegativeInteger.arguments.length > 1)

        secondArg = isNegativeInteger.arguments[1];



    // The next line is a bit byzantine.  What it means is:

    // a) s must be a signed integer, AND

    // b) one of the following must be true:

    //    i)  s is empty and we are supposed to return true for

    //        empty strings

    //    ii) this is a negative, not positive, number



    return (isSignedInteger(s, secondArg)

         && ( (isEmpty(s) && secondArg)  || (parseInt (s) < 0) ) );

}













// isNonpositiveInteger (STRING s [, BOOLEAN emptyOK])

// 

// Returns true if string s is an integer <= 0.

//

// For explanation of optional argument emptyOK,

// see comments of function isInteger.



function isNonpositiveInteger (s)

{   var secondArg = defaultEmptyOK;



    if (isNonpositiveInteger.arguments.length > 1)

        secondArg = isNonpositiveInteger.arguments[1];



    // The next line is a bit byzantine.  What it means is:

    // a) s must be a signed integer, AND

    // b) one of the following must be true:

    //    i)  s is empty and we are supposed to return true for

    //        empty strings

    //    ii) this is a number <= 0



    return (isSignedInteger(s, secondArg)

         && ( (isEmpty(s) && secondArg)  || (parseInt (s) <= 0) ) );

}







// isFloat (STRING s [, BOOLEAN emptyOK])

// 

// True if string s is an unsigned floating point (real) number. 

//

// Also returns true for unsigned integers. If you wish

// to distinguish between integers and floating point numbers,

// first call isInteger, then call isFloat.

//

// Does not accept exponential notation.

//

// For explanation of optional argument emptyOK,

// see comments of function isInteger.



function isFloat (s)



{   var i;

    var seenDecimalPoint = false;



    if (isEmpty(s)) 

       if (isFloat.arguments.length == 1) return defaultEmptyOK;

       else return (isFloat.arguments[1] == true);



    if (s == decimalPointDelimiter) return false;



    // Search through string's characters one by one

    // until we find a non-numeric character.

    // When we do, return false; if we don't, return true.



    for (i = 0; i < s.length; i++)

    {   

        // Check that current character is number.

        var c = s.charAt(i);



        if ((c == decimalPointDelimiter) && !seenDecimalPoint) seenDecimalPoint = true;

        else if (!isDigit(c)) return false;

    }



    // All characters are numbers.

    return true;

}















// isSignedFloat (STRING s [, BOOLEAN emptyOK])

// 

// True if string s is a signed or unsigned floating point 

// (real) number. First character is allowed to be + or -.

//

// Also returns true for unsigned integers. If you wish

// to distinguish between integers and floating point numbers,

// first call isSignedInteger, then call isSignedFloat.

//

// Does not accept exponential notation.

//

// For explanation of optional argument emptyOK,

// see comments of function isInteger.



function isSignedFloat (s)



{   if (isEmpty(s)) 

       if (isSignedFloat.arguments.length == 1) return defaultEmptyOK;

       else return (isSignedFloat.arguments[1] == true);



    else {

        var startPos = 0;

        var secondArg = defaultEmptyOK;



        if (isSignedFloat.arguments.length > 1)

            secondArg = isSignedFloat.arguments[1];



        // skip leading + or -

        if ( (s.charAt(0) == "-") || (s.charAt(0) == "+") )

           startPos = 1;    

        return (isFloat(s.substring(startPos, s.length), secondArg))

    }

}









// isAlphabetic (STRING s [, BOOLEAN emptyOK])

// 

// Returns true if string s is English letters 

// (A .. Z, a..z) only.

//

// For explanation of optional argument emptyOK,

// see comments of function isInteger.

//

// NOTE: Need i18n version to support European characters.

// This could be tricky due to different character

// sets and orderings for various languages and platforms.



function isAlphabetic (s)



{   var i;



    if (isEmpty(s)) 

       if (isAlphabetic.arguments.length == 1) return defaultEmptyOK;

       else return (isAlphabetic.arguments[1] == true);



    // Search through string's characters one by one

    // until we find a non-alphabetic character.

    // When we do, return false; if we don't, return true.



    for (i = 0; i < s.length; i++)

    {   

        // Check that current character is letter.

        var c = s.charAt(i);



        if (!isLetter(c))

        return false;

    }



    // All characters are letters.

    return true;

}









// isAlphanumeric (STRING s [, BOOLEAN emptyOK])

// 

// Returns true if string s is English letters 

// (A .. Z, a..z) and numbers only.

//

// For explanation of optional argument emptyOK,

// see comments of function isInteger.

//

// NOTE: Need i18n version to support European characters.

// This could be tricky due to different character

// sets and orderings for various languages and platforms.



function isAlphanumeric (s)



{   var i;



    if (isEmpty(s)) 

       if (isAlphanumeric.arguments.length == 1) return defaultEmptyOK;

       else return (isAlphanumeric.arguments[1] == true);



    // Search through string's characters one by one

    // until we find a non-alphanumeric character.

    // When we do, return false; if we don't, return true.



    for (i = 0; i < s.length; i++)

    {   

        // Check that current character is number or letter.

        var c = s.charAt(i);



        if (! (isLetter(c) || isDigit(c) ) )

        return false;

    }



    // All characters are numbers or letters.

    return true;

}









// reformat (TARGETSTRING, STRING, INTEGER, STRING, INTEGER ... )       

//

// Handy function for arbitrarily inserting formatting characters

// or delimiters of various kinds within TARGETSTRING.

//

// reformat takes one named argument, a string s, and any number

// of other arguments.  The other arguments must be integers or

// strings.  These other arguments specify how string s is to be

// reformatted and how and where other strings are to be inserted

// into it.

//

// reformat processes the other arguments in order one by one.

// * If the argument is an integer, reformat appends that number 

//   of sequential characters from s to the resultString.

// * If the argument is a string, reformat appends the string

//   to the resultString.

//

// NOTE: The first argument after TARGETSTRING must be a string.

// (It can be empty.)  The second argument must be an integer.

// Thereafter, integers and strings must alternate.  This is to

// provide backward compatibility to Navigator 2.0.2 JavaScript

// by avoiding use of the typeof operator.

//

// It is the caller's responsibility to make sure that we do not

// try to copy more characters from s than s.length.

//

// EXAMPLES:

//

// * To reformat a 10-digit U.S. phone number from "1234567890"

//   to "(123) 456-7890" make this function call:

//   reformat("1234567890", "(", 3, ") ", 3, "-", 4)

//

// * To reformat a 9-digit U.S. Social Security number from

//   "123456789" to "123-45-6789" make this function call:

//   reformat("123456789", "", 3, "-", 2, "-", 4)

//

// HINT:

//

// If you have a string which is already delimited in one way

// (example: a phone number delimited with spaces as "123 456 7890")

// and you want to delimit it in another way using function reformat,

// call function stripCharsNotInBag to remove the unwanted 

// characters, THEN call function reformat to delimit as desired.

//

// EXAMPLE:

//

// reformat (stripCharsNotInBag ("123 456 7890", digits),

//           "(", 3, ") ", 3, "-", 4)



function reformat (s)



{   var arg;

    var sPos = 0;

    var resultString = "";



    for (var i = 1; i < reformat.arguments.length; i++) {

       arg = reformat.arguments[i];

       if (i % 2 == 1) resultString += arg;

       else {

           resultString += s.substring(sPos, sPos + arg);

           sPos += arg;

       }

    }

    return resultString;

}











// isSSN (STRING s [, BOOLEAN emptyOK])

// 

// isSSN returns true if string s is a valid U.S. Social

// Security Number.  Must be 9 digits.

//

// NOTE: Strip out any delimiters (spaces, hyphens, etc.)

// from string s before calling this function.

//

// For explanation of optional argument emptyOK,

// see comments of function isInteger.



function isSSN (s)

{   if (isEmpty(s)) 

       if (isSSN.arguments.length == 1) return defaultEmptyOK;

       else return (isSSN.arguments[1] == true);

    return (isInteger(s) && s.length == digitsInSocialSecurityNumber)

}









// isUSPhoneNumber (STRING s [, BOOLEAN emptyOK])

// 

// isUSPhoneNumber returns true if string s is a valid U.S. Phone

// Number.  Must be 10 digits.

//

// NOTE: Strip out any delimiters (spaces, hyphens, parentheses, etc.)

// from string s before calling this function.

//

// For explanation of optional argument emptyOK,

// see comments of function isInteger.



function isUSPhoneNumber (s)

{   if (isEmpty(s)) 

       if (isUSPhoneNumber.arguments.length == 1) return defaultEmptyOK;

       else return (isUSPhoneNumber.arguments[1] == true);

    return (isInteger(s) && s.length == digitsInUSPhoneNumber)

}









// isInternationalPhoneNumber (STRING s [, BOOLEAN emptyOK])

// 

// isInternationalPhoneNumber returns true if string s is a valid 

// international phone number.  Must be digits only; any length OK.

// May be prefixed by + character.

//

// NOTE: A phone number of all zeros would not be accepted.

// I don't think that is a valid phone number anyway.

//

// NOTE: Strip out any delimiters (spaces, hyphens, parentheses, etc.)

// from string s before calling this function.  You may leave in 

// leading + character if you wish.

//

// For explanation of optional argument emptyOK,

// see comments of function isInteger.



function isInternationalPhoneNumber (s)

{   if (isEmpty(s)) 

       if (isInternationalPhoneNumber.arguments.length == 1) return defaultEmptyOK;

       else return (isInternationalPhoneNumber.arguments[1] == true);

    return (isPositiveInteger(s))

}









// isZIPCode (STRING s [, BOOLEAN emptyOK])

// 

// isZIPCode returns true if string s is a valid 

// U.S. ZIP code.  Must be 5 or 9 digits only.

//

// NOTE: Strip out any delimiters (spaces, hyphens, etc.)

// from string s before calling this function.  

//

// For explanation of optional argument emptyOK,

// see comments of function isInteger.



function isZIPCode (s)

{  if (isEmpty(s)) 

       if (isZIPCode.arguments.length == 1) return defaultEmptyOK;

       else return (isZIPCode.arguments[1] == true);

   return (isInteger(s) && 

            ((s.length == digitsInZIPCode1) ||

             (s.length == digitsInZIPCode2)))

}







// isStateCode (STRING s [, BOOLEAN emptyOK])

// 

// Return true if s is a valid U.S. Postal Code 

// (abbreviation for state).

//

// For explanation of optional argument emptyOK,

// see comments of function isInteger.



function isStateCode(s)

{   if (isEmpty(s)) 

       if (isStateCode.arguments.length == 1) return defaultEmptyOK;

       else return (isStateCode.arguments[1] == true);

    return ( (USStateCodes.indexOf(s) != -1) &&

             (s.indexOf(USStateCodeDelimiter) == -1) )

}









// isEmail (STRING s [, BOOLEAN emptyOK])

// 

// Email address must be of form a@b.c -- in other words:

// * there must be at least one character before the @

// * there must be at least one character before and after the .

// * the characters @ and . are both required

//

// For explanation of optional argument emptyOK,

// see comments of function isInteger.



function isEmail (s)

{   if (isEmpty(s)) 

       if (isEmail.arguments.length == 1) return defaultEmptyOK;

       else return (isEmail.arguments[1] == true);

   

    // is s whitespace?

    if (isWhitespace(s)) return false;

    

    // there must be >= 1 character before @, so we

    // start looking at character position 1 

    // (i.e. second character)

    var i = 1;

    var sLength = s.length;



    // look for @

    while ((i < sLength) && (s.charAt(i) != "@"))

    { i++

    }



    if ((i >= sLength) || (s.charAt(i) != "@")) return false;

    else i += 2;



    // look for .

    while ((i < sLength) && (s.charAt(i) != "."))

    { i++

    }



    // there must be at least one character after the .

    if ((i >= sLength - 1) || (s.charAt(i) != ".")) return false;

    else return true;

}



// isYear (STRING s [, BOOLEAN emptyOK])

// 

// isYear returns true if string s is a valid 

// Year number.  Must be 2 or 4 digits only.

// 

// For Year 2000 compliance, you are advised

// to use 4-digit year numbers everywhere.

//

// And yes, this function is not Year 10000 compliant, but 

// because I am giving you 8003 years of advance notice,

// I don't feel very guilty about this ...

//

// For B.C. compliance, write your own function. ;->

//

// For explanation of optional argument emptyOK,

// see comments of function isInteger.



function isYear (s)

{   if (isEmpty(s)) 

       if (isYear.arguments.length == 1) return defaultEmptyOK;

       else return (isYear.arguments[1] == true);

    if (!isNonnegativeInteger(s)) return false;

    return (s.length == 4);

}







// isIntegerInRange (STRING s, INTEGER a, INTEGER b [, BOOLEAN emptyOK])

// 

// isIntegerInRange returns true if string s is an integer 

// within the range of integer arguments a and b, inclusive.

// 

// For explanation of optional argument emptyOK,

// see comments of function isInteger.





function isIntegerInRange (s, a, b)

{   if (isEmpty(s)) 

       if (isIntegerInRange.arguments.length == 1) return defaultEmptyOK;

       else return (isIntegerInRange.arguments[1] == true);



    // Catch non-integer strings to avoid creating a NaN below,

    // which isn't available on JavaScript 1.0 for Windows.

    if (!isInteger(s, false)) return false;



    // Now, explicitly change the type to integer via parseInt

    // so that the comparison code below will work both on 

    // JavaScript 1.2 (which typechecks in equality comparisons)

    // and JavaScript 1.1 and before (which doesn't).

    var num = parseInt (s);

    return ((num >= a) && (num <= b));

}







// isMonth (STRING s [, BOOLEAN emptyOK])

// 

// isMonth returns true if string s is a valid 

// month number between 1 and 12.

//

// For explanation of optional argument emptyOK,

// see comments of function isInteger.



function isMonth (s)

{   if (isEmpty(s)) 

       if (isMonth.arguments.length == 1) return defaultEmptyOK;

       else return (isMonth.arguments[1] == true);

    return isIntegerInRange (s, 1, 12);

}







// isDay (STRING s [, BOOLEAN emptyOK])

// 

// isDay returns true if string s is a valid 

// day number between 1 and 31.

// 

// For explanation of optional argument emptyOK,

// see comments of function isInteger.



function isDay (s)

{   if (isEmpty(s)) 

       if (isDay.arguments.length == 1) return defaultEmptyOK;

       else return (isDay.arguments[1] == true);   

    return isIntegerInRange (s, 1, 31);

}







// daysInFebruary (INTEGER year)

// 

// Given integer argument year,

// returns number of days in February of that year.



function daysInFebruary (year)

{   // February has 29 days in any year evenly divisible by four,

    // EXCEPT for centurial years which are not also divisible by 400.

    return (  ((year % 4 == 0) && ( (!(year % 100 == 0)) || (year % 400 == 0) ) ) ? 29 : 28 );

}







// isDate (STRING year, STRING month, STRING day)

//

// isDate returns true if string arguments year, month, and day 

// form a valid date.

// 



function isDate (year, month, day)

{   // catch invalid years (not 2- or 4-digit) and invalid months and days.

    if (! (isYear(year, false) && isMonth(month, false) && isDay(day, false))) return false;



    // Explicitly change type to integer to make code work in both

    // JavaScript 1.1 and JavaScript 1.2.

    var intYear = parseInt(year);

    var intMonth = parseInt(month);

    var intDay = parseInt(day);



    // catch invalid days, except for February

    if (intDay > daysInMonth[intMonth]) return false; 



    if ((intMonth == 2) && (intDay > daysInFebruary(intYear))) return false;



    return true;

}









/* FUNCTIONS TO NOTIFY USER OF INPUT REQUIREMENTS OR MISTAKES. */





// Display prompt string s in status bar.



function prompt (s)

{   window.status = s

}







// Display data entry prompt string s in status bar.



function promptEntry (s)

{   window.status = pEntryPrompt + s

}









// Notify user that required field theField is empty.

// String s describes expected contents of theField.value.

// Put focus in theField and return false.



function warnEmpty (theField, s)

{   

    alert(mPrefix + s + mSuffix)

    theField.focus()

    return false

}







// Notify user that contents of field theField are invalid.

// String s describes expected contents of theField.value.

// Put select theField, pu focus in it, and return false.



function warnInvalid (theField, s)

{   

    theField.select()

    alert(s)

    theField.focus()

    return false

}









/* FUNCTIONS TO INTERACTIVELY CHECK VARIOUS FIELDS. */



// checkString (TEXTFIELD theField, STRING s, [, BOOLEAN emptyOK==false])

//

// Check that string theField.value is not all whitespace.

//

// For explanation of optional argument emptyOK,

// see comments of function isInteger.



function checkString (theField, s, emptyOK)

{   // Next line is needed on NN3 to avoid "undefined is not a number" error

    // in equality comparison below.

    if (checkString.arguments.length == 2) emptyOK = defaultEmptyOK;

    if ((emptyOK == true) && (isEmpty(theField.value))) return true;

    if (isWhitespace(theField.value)) 

       return warnEmpty (theField, s);

       

    else return true;

}





// checkStateCode (TEXTFIELD theField [, BOOLEAN emptyOK==false])

//

// Check that string theField.value is a valid U.S. state code.

//

// For explanation of optional argument emptyOK,

// see comments of function isInteger.



function checkStateCode (theField, emptyOK)

{   if (checkStateCode.arguments.length == 1) emptyOK = defaultEmptyOK;

    if ((emptyOK == true) && (isEmpty(theField.value))) return true;

    else

    {  theField.value = theField.value.toUpperCase();

       if (!isStateCode(theField.value, false)) 

          return warnInvalid (theField, iStateCode);

       else return true;

    }

}







// takes ZIPString, a string of 5 or 9 digits;

// if 9 digits, inserts separator hyphen



function reformatZIPCode (ZIPString)

{   if (ZIPString.length == 5) return ZIPString;

    else return (reformat (ZIPString, "", 5, "-", 4));

}









// checkZIPCode (TEXTFIELD theField [, BOOLEAN emptyOK==false])

//

// Check that string theField.value is a valid ZIP code.

//

// For explanation of optional argument emptyOK,

// see comments of function isInteger.



function checkZIPCode (theField, emptyOK)

{   if (checkZIPCode.arguments.length == 1) emptyOK = defaultEmptyOK;

    if ((emptyOK == true) && (isEmpty(theField.value))) return true;

    else

    { var normalizedZIP = stripCharsInBag(theField.value, ZIPCodeDelimiters)

      if (!isZIPCode(normalizedZIP, false)) 

         return warnInvalid (theField, iZIPCode);

      else 

      {  // if you don't want to insert a hyphen, comment next line out

         theField.value = reformatZIPCode(normalizedZIP)

         return true;

      }

    }

}







// takes USPhone, a string of 10 digits

// and reformats as (123) 456-789



function reformatUSPhone (USPhone)

{   return (reformat (USPhone, "(", 3, ") ", 3, "-", 4))

}







// checkUSPhone (TEXTFIELD theField [, BOOLEAN emptyOK==false])

//

// Check that string theField.value is a valid US Phone.

//

// For explanation of optional argument emptyOK,

// see comments of function isInteger.



function checkUSPhone (theField, emptyOK)

{   if (checkUSPhone.arguments.length == 1) emptyOK = defaultEmptyOK;

    if ((emptyOK == true) && (isEmpty(theField.value))) return true;

    else

    {  var normalizedPhone = stripCharsInBag(theField.value, phoneNumberDelimiters)

       if (!isUSPhoneNumber(normalizedPhone, false)) 

          return warnInvalid (theField, iUSPhone);

       else 

       {  // if you don't want to reformat as (123) 456-789, comment next line out

          theField.value = reformatUSPhone(normalizedPhone)

          return true;

       }

    }

}





function checkMonthsExp (theField, emptyOK)

{   if (checkMonthsExp.arguments.length == 1) emptyOK = defaultEmptyOK;

    if ((emptyOK == true) && (isEmpty(theField.value))) return true;

    else

    {  if (!isInteger(theField.value, false)) 

          return warnInvalid (theField, "You must enter a numeric value for months of experience.");

       else

		  return true;

    }

}









// checkInternationalPhone (TEXTFIELD theField [, BOOLEAN emptyOK==false])

//

// Check that string theField.value is a valid International Phone.

//

// For explanation of optional argument emptyOK,

// see comments of function isInteger.



function checkInternationalPhone (theField, emptyOK)

{   if (checkInternationalPhone.arguments.length == 1) emptyOK = defaultEmptyOK;

    if ((emptyOK == true) && (isEmpty(theField.value))) return true;

    else 

		var thisPhone = (stripCharsInBag(theField.value,phoneNumberDelimiters));

    {  if (!isInternationalPhoneNumber(thisPhone, false))

          return warnInvalid (theField, iWorldPhone);

       else return true;

    }

}







// checkEmail (TEXTFIELD theField [, BOOLEAN emptyOK==false])

//

// Check that string theField.value is a valid Email.

//

// For explanation of optional argument emptyOK,

// see comments of function isInteger.



function checkEmail (theField, emptyOK)

{   if (checkEmail.arguments.length == 1) emptyOK = defaultEmptyOK;

    if ((emptyOK == true) && (isEmpty(theField.value))) return true;

    else if (!isEmail(theField.value, false)) 

       return warnInvalid (theField, iEmail);

    else return true;

}







// takes SSN, a string of 9 digits

// and reformats as 123-45-6789



function reformatSSN (SSN)

{   return (reformat (SSN, "", 3, "-", 2, "-", 4))

}





// Check that string theField.value is a valid SSN.

//

// For explanation of optional argument emptyOK,

// see comments of function isInteger.



function checkSSN (theField, emptyOK)

{   if (checkSSN.arguments.length == 1) emptyOK = defaultEmptyOK;

    if ((emptyOK == true) && (isEmpty(theField.value))) return true;

    else

    {  var normalizedSSN = stripCharsInBag(theField.value, SSNDelimiters)

       if (!isSSN(normalizedSSN, false)) 

          return warnInvalid (theField, iSSN);

       else 

       {  // if you don't want to reformats as 123-456-7890, comment next line out

          theField.value = reformatSSN(normalizedSSN)

          return true;

       }

    }

}









// Check that string theField.value is a valid Year.

//

// For explanation of optional argument emptyOK,

// see comments of function isInteger.



function checkYear (theField, emptyOK)

{   if (checkYear.arguments.length == 1) emptyOK = defaultEmptyOK;

    if ((emptyOK == true) && (isEmpty(theField.value))) return true;

    if (!isYear(theField.value, false)) 

       return warnInvalid (theField, iYear);

    else return true;

}





// Check that string theField.value is a valid Month.

//

// For explanation of optional argument emptyOK,

// see comments of function isInteger.



function checkMonth (theField, emptyOK)

{   if (checkMonth.arguments.length == 1) emptyOK = defaultEmptyOK;

    if ((emptyOK == true) && (isEmpty(theField.value))) return true;

    if (!isMonth(theField.value, false)) 

       return warnInvalid (theField, iMonth);

    else return true;

}





// Check that string theField.value is a valid Day.

//

// For explanation of optional argument emptyOK,

// see comments of function isInteger.



function checkDay (theField, emptyOK)

{   if (checkDay.arguments.length == 1) emptyOK = defaultEmptyOK;

    if ((emptyOK == true) && (isEmpty(theField.value))) return true;

    if (!isDay(theField.value, false)) 

       return warnInvalid (theField, iDay);

    else return true;

}







// checkDate (yearField, monthField, dayField, STRING labelString [, OKtoOmitDay==false])

//

// Check that yearField.value, monthField.value, and dayField.value 

// form a valid date.

//

// If they don't, labelString (the name of the date, like "Birth Date")

// is displayed to tell the user which date field is invalid.

//

// If it is OK for the day field to be empty, set optional argument

// OKtoOmitDay to true.  It defaults to false.



function checkDate (yearField, monthField, dayField, labelString, OKtoOmitDay)

{   // Next line is needed on NN3 to avoid "undefined is not a number" error

    // in equality comparison below.

    if (checkDate.arguments.length == 4) OKtoOmitDay = false;

    if (!isYear(yearField.value)) return warnInvalid (yearField, iYear);

    if (!isMonth(monthField.value)) return warnInvalid (monthField, iMonth);

    if ( (OKtoOmitDay == true) && isEmpty(dayField.value) ) return true;

    else if (!isDay(dayField.value)) 

       return warnInvalid (dayField, iDay);

    if (isDate (yearField.value, monthField.value, dayField.value))

       return true;

    else {

	    dayField.focus();

		alert (iDatePrefix + labelString + iDateSuffix)

		return false

		}

}







// Get checked value from radio button.



function getRadioButtonValue (radio)

{   for (var i = 0; i < radio.length; i++)

    {   if (radio[i].checked) { break }

    }

    return radio[i].value

}