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https://github.com/braintree/card-validator

Validate credit cards as users type.
https://github.com/braintree/card-validator

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Validate credit cards as users type.

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# Credit Card Validator [![Build Status](https://github.com/braintree/card-validator/workflows/Unit%20Tests/badge.svg)](https://github.com/braintree/card-validator/actions?query=workflow%3A%22Unit+Tests%22) [![npm version](https://badge.fury.io/js/card-validator.svg)](http://badge.fury.io/js/card-validator)



Credit Card Validator provides validation utilities for credit card data inputs. It is designed as a CommonJS module for use in Node.js, io.js, or the [browser](http://browserify.org/). It includes first class support for 'potential' validity so you can use it to present appropriate UI to your user as they type.



A typical use case in a credit card form is to notify the user if the data they are entering is invalid. In a credit card field, entering “411” is not necessarily valid for submission, but it is still potentially valid. Conversely, if a user enters “41x” that value can no longer pass strict validation and you can provide a response immediately.



Credit Card Validator will also provide a determined card type (using [credit-card-type](https://github.com/braintree/credit-card-type)). This is useful for scenarios in which you wish to render an accompanying payment method icon (Visa, MasterCard, etc.). Additionally, by having access to the current card type, you can better manage the state of your credit card form as a whole. For example, if you detect a user is entering (or has entered) an American Express card number, you can update the `maxlength` attribute of your `CVV` input element from 3 to 4 and even update the corresponding `label` from 'CVV' to 'CID'.



## Download



You can install `card-validator` through `npm`.



```

npm install card-validator

```



## Example



### Using a CommonJS build tool (browserify, webpack, etc)



```javascript

var valid = require("card-validator");



var numberValidation = valid.number("4111");



if (!numberValidation.isPotentiallyValid) {

  renderInvalidCardNumber();

}



if (numberValidation.card) {

  console.log(numberValidation.card.type); // 'visa'

}

```



## API



### `var valid = require('card-validator');`



---



#### `valid.number(value: string, [options: object]): object`



```javascript

{

  card: {

    niceType: 'American Express',

    type: 'american-express',

    gaps: [4, 10],

    lengths: [15],

    code: {name: 'CID', size: 4}

  },

  isPotentiallyValid: true, // if false, indicates there is no way the card could be valid

  isValid: true // if true, number is valid for submission

}

```



You can optionally pass `luhnValidateUnionPay` as a property of an object as a second argument. This will override the default behavior to ignore luhn validity of UnionPay cards.



```javascript

valid.number(, {luhnValidateUnionPay: true});



{

  card: {

    niceType: 'UnionPay',

    type: 'unionpay',

    gaps: [4, 8, 12],

    lengths: [16, 17, 18, 19],

    code: {name: 'CVN', size: 3}

  },

  isPotentiallyValid: true,

  isValid: false // Would be true if no options were included

}

```



You can optionally pass `maxLength` as a property of an object as a second argument. This will override the default behavior to use the card type's max length property and mark any cards that exceed the max length as invalid.



If a card brand has a normal max length that is shorter than the passed in max length, the validator will use the shorter one. For instance, if a `maxLength` of `16` is provided, the validator will still use `15` as the max length for American Express cards.



You can optionally pass `skipLuhnValidation: true` as a property of an object as a second argument. This will override the default behaviour and will skip the validation of the check digit of the card number using Luhn Algorithm. The `skipLuhnValidation` **should not** be set to `true` in production environment.



```javascript

valid.number(, {maxLength: 16});



{

  card: {

    // Maestro card data

  },

  isPotentiallyValid: false,

  isValid: false

}

```



If a valid card type cannot be determined, the `card` field in the response will be `null`.



A fake session where a user is entering a card number may look like:



  

    

      Input

      Output

      Suggested Handling

    

  

  

    

      Value

      card.type

      isPotentiallyValid

      isValid

      Render Invalid UI

      Allow Submit

    

  

  

    

      ''

      null

      true

      false

      no

      no

    

    

      '6'

      null

      true

      false

      no

      no

    

    

      '60'

      'discover'

      true

      false

      no

      no

    

    

      '601'

      'discover'

      true

      false

      no

      no

    

    

      '6011'

      'discover'

      true

      false

      no

      no

    

    

      '601'

      'discover'

      true

      false

      no

      no

    

    

      '60'

      'discover'

      true

      false

      no

      no

    

    

      '6'

      null

      true

      false

      no

      no

    

    

      ''

      null

      true

      false

      no

      no

    

    

      'x'

      null

      false

      false

      yes

      no

    

    

      ''

      null

      true

      false

      no

      no

    

    

      '4'

      'visa'

      true

      false

      no

      no

    

    

      '41'

      'visa'

      true

      false

      no

      no

    

    

      '411'

      'visa'

      true

      false

      no

      no

    

    

      '4111111111111111'

      'visa'

      true

      true

      no

      yes

    

    

      '411x'

      null

      false

      false

      yes

      no

    

  



---



#### `valid.cardholderName(value: string): object`



The `cardholderName` validation essentially tests for a valid string greater than 0 characters in length that does not look like a card number.



```javascript

{

  isPotentiallyValid: true,

  isValid: true

}

```



If a cardholder name is comprised of only numbers, hyphens and spaces, the validator considers it to be too card-like to be valid, but may still be potentially valid if a non-numeric character is added. This is to prevent card number values from being sent along as the cardholder name but not make too many assumptions about a person's cardholder name.



```javascript

{

  isPotentiallyValid: true,

  isValid: false

}

```



If a cardholder name is longer than 255 characters, it is assumed to be invalid.



```javascript

{

  isPotentiallyValid: false,

  isValid: false

}

```



#### `valid.expirationDate(value: string|object, maxElapsedYear: integer): object`



The `maxElapsedYear` parameter determines how many years in the future a card's expiration date should be considered valid. It has a default value of 19, so cards with an expiration date 20 or more years in the future would not be considered valid. It can be overridden by passing in an `integer` as a second argument.



```javascript

{

  isPotentiallyValid: true, // if false, indicates there is no way this could be valid in the future

  isValid: true,

  month: '10', // a string with the parsed month if valid, null if either month or year are invalid

  year: '2016' // a string with the parsed year if valid, null if either month or year are invalid

}

```



`expirationDate` will parse strings in a variety of formats:



| Input                                                                                       | Output                        |

| ------------------------------------------------------------------------------------------- | ----------------------------- |

| `'10/19'`
`'10 / 19'`
`'1019'`
`'10 19'`                                       | `{month: '10', year: '19'}`   |

| `'10/2019'`
`'10 / 2019'`
`'102019'`
`'10 2019'`
`'10 19'`                 | `{month: '10', year: '2019'}` |

| `'2019-10'`                                                                                 | `{month: '10', year: '2019'}` |

| `{month: '01', year: '19'}`
`{month: '1', year: '19'}`
`{month: 1, year: 19}`       | `{month: '01', year: '19'}`   |

| `{month: '01', year: '2019'}`
`{month: '1', year: '2019'}`
`{month: 1, year: 2019}` | `{month: '01', year: '2019'}` |



---



#### `valid.expirationMonth(value: string): object`



`expirationMonth` accepts 1 or 2 digit months. `1`, `01`, `10` are all valid entries.



```javascript

{

  isValidForThisYear: false,

  isPotentiallyValid: true,

  isValid: true

}

```



---



#### `valid.expirationYear(value: string, maxElapsedYear: integer): object`



`expirationYear` accepts 2 or 4 digit years. `16` and `2016` are both valid entries.



The `maxElapsedYear` parameter determines how many years in the future a card's expiration date should be considered valid. It has a default value of 19, so cards with an expiration date 20 or more years in the future would not be considered valid. It can be overridden by passing in an `integer` as a second argument.



```javascript

{

  isCurrentYear: false,

  isPotentiallyValid: true,

  isValid: true

}

```



---



#### `valid.cvv(value: string, maxLength: integer): object`



The `cvv` validation by default tests for a numeric string of 3 characters in length. The `maxLength` can be overridden by passing in an `integer` as a second argument. You would typically switch this length from 3 to 4 in the case of an American Express card which expects a 4 digit CID.



```javascript

{

  isPotentiallyValid: true,

  isValid: true

}

```



---



#### `valid.postalCode(value: string, [options: object]): object`



The `postalCode` validation essentially ignores leading/trailing whitespace and tests for a valid string greater than 3 characters in length. It also verifies that the first 3 letters are alphanumeric.



```javascript

{

  isPotentiallyValid: true,

  isValid: true

}

```



You can optionally pass `minLength` as a property of an object as a second argument. This will override the default min length of 3 and verify that the characters for the specified length are all alphanumeric.



```javascript

valid.postalCode('123', {minLength: 5});



{

  isPotentiallyValid: true,

  isValid: false

}

```



## Custom Card Brands



Card Validator exposes the [`credit-card-type` module](https://github.com/braintree/credit-card-type) as `creditCardType`. You can add custom card brands by [utilizing the `addCard` method](https://github.com/braintree/credit-card-type#adding-card-types).



```javascript

valid.creditCardType.addCard({

  niceType: "NewCard",

  type: "new-card",

  patterns: [1234],

  gaps: [4, 8, 12],

  lengths: [16],

  code: {

    name: "CVV",

    size: 3,

  },

});

```



## Design decisions



- The default maximum expiration year is 19 years from now.

- `valid.expirationDate` will only return `month:` and `year:` as strings if the two are valid, otherwise they will be `null`.

- Since non-US postal codes are alpha-numeric, the `postalCode` will allow non-number characters to be used in validation.



## Development



We use `nvm` for managing our node versions, but you do not have to. Replace any `nvm` references with the tool of your choice below.



```sh

nvm install

npm install

```



All testing dependencies will be installed upon `npm install`. Run the test suite with `npm test`.