#Credit card validator javascript code

Note also that this script handles preliminary validation only and does not contain any code relating to security. To properly validate credit card numbers requires server side processing but this code will help you to reject many invalid numbers before the server side routine needs to be called. No cards are tested for credit capability in this routine. Cards rejected by the routine are definitely not valid. Numbers accepted by this code COULD be valid credit card numbers but may not actually correspond to a card that has been issued. This routine only tests if the number entered is the right length to be a credit card number and contains the correct check digit. The function will return true if the number supplied is the correct length and COULD be a credit card number otherwise, it will return false if it is definitely not a valid card number. Pass the field to be validated (non-numerics in the field will be ignored). You can apply this validation to your own credit card number fields by calling the following validation routine from the point in your code you wish to perform the validation. An alert box will display to tell you whether the number entered COULD be a valid credit card number. There are still many possible invalid card numbers that would be accepted by this routine and would not be picked up until later but the script does reject 90% of all possible number combinations (all valid numbers are within the remaining 10% that the script lets through).Įnter something into the above credit card validation test field then click the validate button. The actual values used in some of the positions within the number also have special meanings (such as card issuer, country of issue, etc.) but this routine does not check for those. (It also restricts the field input to numeric).

The following field will test a card number for appropriate length as well as confirming that the number has a valid 'check digit'. What you can do with Javascript is to test the number that is entered to see if it could be a valid credit card number.

This means that only certain number combinations are valid. The card numbers also contain what is called a 'check digit' to help ensure that if you transpose digits in the entered credit card number that you are not accidentally quoting a number belonging to someone else. Some other credit card numbering systems vary. American Express starts with the number 34 or 37.This script is designed to validate using Javascript's client capabilites that the number that is entered COULD possibly be a valid credit card number.Ĭredit card numbers are all numeric and have fixed lengths (13 digits for Diners Club, 15 for American Express, and 16 digits for all the others). MasterCards start with the number 51, 52, 53, 54, or 55. The checksum 60 ends with the number 0, therefore it a syntactically sound credit card number Identifying Credit Card TypesĪside from the checksum, credit card number numbers also identify the type of credit card company. Starting from the second-to-last-digit, multiply the last number by 2.ġ + 4 + 1 + 4 + 8 + 1 + 8 +1 + 2 + 2 + 0 = 32įinally add the digits that were not multiplied to the sum Take for example the following American Express number, 378734493671000. If the total’s last digit is 0 then the number is valid! Multiply every other digit by 2, starting with the number’s second-to-last digit, and then add those products’ digits together.Īdd the sum to the sum of the digits that weren’t multiplied by 2. Here’s a simple break down on Luhn’s algorithm. The process of validation checking is based on a checksum algorithm created by Hans Peter Luhn. Usually at the front end, Javascript would handle the validation to check if the credit card is a valid card before a call is sent to the servers. Most of us have encountered this screen when trying to make a payment for an online purchase.

Credit card validator javascript