Credit Card Validation: You\'re starting your own credit card business. You\'ve

ID: 3717145 • Letter: C

Question

Credit Card Validation:

You're starting your own credit card business. You've come up with a new way to validate

credit cards with a simple function called validateCreditCard that returns true or false.

Here are the rules for a valid number:

Number must be 16 digits, all of them must be numbers

You must have at least two different digits represented (all of the digits cannot be the same)

The final digit must be even

The sum of all the digits must be greater than 16

The following credit card numbers are valid:

9999-9999-8888-0000

6666-6666-6666-1666

The following credit card numbers are invalid:

a923-3211-9c01-1112 invalid characters

4444-4444-4444-4444 only one type of number

1111-1111-1111-1110 sum less than 16

6666-6666-6666-6661 odd final number

Return an object indicating whether the credit card is valid,

and if not, what the error is{ valid: true, number: 'a923-3211-9c01-1112' }

{ valid: false, number: 'a923-3211-9c01-1112', error: ‘wrong_length

Write the above code in Javascript in HTML code

Explanation / Answer

<!DOCTYPE html>

<head>

</head>

<body>

<label>Credit Card: </label>

</body>

</html>

function validateCreditCard(OriginalCardNum) {

var ErrorMsg = "";

//remove the '-' charachters

var CardNum = OriginalCardNum.split('-').join('');

//error if length is not 16

if (CardNum.length != 16)

ErrorMsg = "wrong_length";

//error if final number is odd

else if (CardNum.charAt(15) % 2 != 0)

ErrorMsg = "odd_final_number";

else {

var sameDigits = 0, sumOfDigits = 0;

var firstChar = CardNum.charAt(0), curChar = ' ';

//loop through each cahrachter

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

curChar = CardNum.charAt(i);

//Error if non digit cahr is found

if (isNaN(curChar)) {

ErrorMsg = "invalid_characters";

break;

}

else //Sum of digits

sumOfDigits += parseInt(curChar, 10);

//count the same charachters

if (firstChar == curChar) {

sameDigits++;

}

//now check for errors

if (ErrorMsg == "") {

if (sumOfDigits <= 16) {

//less then 16, show error

ErrorMsg = "sum_less_than_16";

}

//same digits countis 16, show error

else if (sameDigits == 16)

ErrorMsg = "only_one_type_of_number";

}

// Define the object

var obj = {

valid: ErrorMsg == "" ? true : false,

number: OriginalCardNum,

error: ErrorMsg

};

return obj;

}

function validate() {

var object = validateCreditCard(document.getElementById("txtCreditCard").value.trim())

//set the error message to span spnError

document.getElementById("spnError").innerHTML = object.error;

//For modern browsers, if the above line doesn't supports

//document.getElementById("spnError").textContent=object.error;

}

</script>