Function maskBankCard

Utilities for sensitive data

Author

David Hsing

maskBankCard(text?: string | null): string | undefined
Returns a masked bank card number, which keeps the last 4 characters

The card number follows ISO/IEC 7812, so cards issued outside China are supported as well. Note that the Luhn checksum is not verified here, since not all issuers follow it
Parameters
- Optionaltext: string | null
  The text to mask
Returns string | undefined
a masked bank card number, or undefined if the given text is invalid
Author
David Hsing
Example
```
maskBankCard(undefined);    // undefined
maskBankCard('6222021234567890123');    // '**** **** **** *** 0123'
maskBankCard('4111111111111111');    // '**** **** **** 1111'
maskBankCard('378282246310005');    // '**** **** *** 0005'
maskBankCard('62220212');    // undefined
```