maskdata is a Node.js module to mask various kinds of data. With the help of maskdata, you can mask email, phone number, card number, JSON fields, password, etc... Also, it provides utility methods to get a field, or replace a field from any complex/nested JSON.

Table of Contents

• Install maskdata
• Version 1.3.3 Features
• Maskdata for Typescript
• How to Mask
  • Card number
  • Email
  • Password
  • Phone Number
  • Generic String
  • Words/characters in a string
  • UUID
  • JWT Token
  • Object / JSON fields
    • JSON mask examples with nested fields
    • Mask multiple fields at once using .* and [*].
    • Recursive masking / Mask all the fields with a name in the json
  • Get Nested JSON Property
  • Replace the value of a JSON field
• Report Bugs
• Give a Star
• LICENSE - "MIT"

Install maskdata

npm i maskdata

Release Features

Version 1.3.3

• Better documentation
• Bug fix and enabling strings with regex characters in the string mask functionality
  • https://github.com/Sumukha1496/maskdata/issues/49
• Deprecate stringmask v1

Version 1.3.2

• Recursive masking feature: Details
  • https://github.com/Sumukha1496/maskdata/issues/45
  • https://github.com/Sumukha1496/maskdata/issues/47
• Fixed output length masking: Mask Password and Mask String
  • https://github.com/Sumukha1496/maskdata/issues/46

Version 1.3.1

• Removal of maskJSONFields function: https://www.npmjs.com/package/maskdata/v/1.1.10#mask-fields-in-a-json
• String mask version2 for generic string masking in response to the below issues: Details
  • https://github.com/Sumukha1496/maskdata/issues/17
  • https://github.com/Sumukha1496/maskdata/issues/40
  • https://github.com/Sumukha1496/maskdata/issues/42
• Supporting generic string masking(string mask V2) as part of maskJson2: generic String masking in a JSON

Maskdata for Typescript

Follow this document for more details: Maskdata for typescript

How to Mask

const MaskData = require('./maskdata');

Mask card number

This will mask the digits in a card number.This will mask only the numerical data and not any non-numeric delimiters, alphabets, or any other types of data

const MaskData = require('./maskdata');

const maskCardOptions = {
  // Character to mask the data. The default value is '*'
  maskWith: "*",

  // Should be positive Integer
  // If the starting 'n' digits need to be visible/unmasked
  // Default value is 4
  unmaskedStartDigits: 4,

  // Should be positive Integer
  // If the ending 'n' digits need to be visible/unmasked
  // Default value is 1. 
  unmaskedEndDigits: 1 
};

const cardNumber = "1234-5678-1234-5678";

const cardAfterMasking = MaskData.maskCard(cardNumber, maskCardOptions);

//Output: 1234-****-****-***8

Mask Email id

Function to mask email id. Input must have a '@' in it.

const MaskData = require('./maskdata');

const emailMask2Options = {
    // Character to mask the data. The default value is '*'
    maskWith: "*", 
    // If we want to keep the starting 'n' characters before the '@' unmasked.
    // Default value is 3
    unmaskedStartCharactersBeforeAt: 3,
    // If we want to keep the last 'n' characters AFTER the '@' unmasked.
    // Default value is 2
    unmaskedEndCharactersAfterAt: 2,
    // Flag to mask or show '@'. Default value is false means do not mask
    maskAtTheRate: false
};

const email = "[email protected]";

const maskedEmail = MaskData.maskEmail2(email, emailMask2Options);

//Output: my.********@**********om

Consider an email: [email protected]

Here,

• number of characters before @ -> 4
• number of characters after @ --> 9

1. unmaskedStartCharactersBeforeAt --> number of starting characters (before @)not to be masked.
   • If unmaskedStartCharactersBeforeAt > number of characters before @, then it will not mask the characters before @
2. unmaskedEndCharactersAfterAt --> number of characters not to be masked starting from the end till @.
   • If unmaskedEndCharactersAfterAt > number of characters after @, then it will not mask the characters after @

Mask only the characters before '@' / Show only the domain

const MaskData = require('./maskdata');

const emailMask2Options = {
    maskWith: "*", 
    unmaskedStartCharactersBeforeAt: 0, // Set this to 0 to mask the first part
    unmaskedEndCharactersAfterAt: 257, // Enter a large number which is always more than the characters after @
    maskAtTheRate: false
};

const email = "[email protected]";

const maskedEmail = MaskData.maskEmail2(email, emailMask2Options);

//Output: ****@email.com

Mask Password

const MaskData = require('./maskdata');

const maskPasswordOptions = {
  // Character to mask the data
  // default value is '*'
  maskWith: "*",

  // To limit the *s in the response when the password length is more
  // Default value is 16
  maxMaskedCharacters: 16,

  // To fix the length of output irrespective of the length of the input. This comes in handy when the input length < maxMaskedCharacters but we want a fixed output length.
  // Default value is undefined. If this value is set, then maxMaskedCharacters will not be considered and the output length will always be equal to fixedOutputLength characters.
  fixedOutputLength: undefined,

  // To show(not mask) first 'n' characters in the password/secret key. 
  // Default value is 0. 
  unmaskedStartCharacters: 0,

  // To show(not mask) last 'n' characters in the password/secret key. 
  // Default value is 0. 
  unmaskedEndCharacters: 0
};

const password = "Password1$";

const maskedPassword = MaskData.maskPassword(password, maskPasswordOptions);

//Output: **********

## Mask Password with the default configuration
To mask with the default options, don't pass the configurations.
```javascript
const MaskData = require('./maskdata');

  /** Default Options
    maskWith: "*"
    maxMaskedCharacters: 16,
    unmaskedStartCharacters: 0,
    fixedOutputLength: undefined,
    unmaskedEndCharacters: 0
  **/

const password = "Password1$";

const maskedPassword = MaskData.maskPassword(password)

Example: Mask password OR secretKey with some meta info at the end

const MaskData = require('./maskdata');

const maskPasswordOptions = {
  maskWith: "X",
  maxMaskedCharacters: 20, // To limit the output String length to 20.
  unmaskedStartCharacters: 4,
  unmaskedEndCharacters: 9, // As the last 9 characters of the secret key is meta info which can be printed for debugging or other purposes
  fixedOutputLength: undefined
};

const password = "TEST:U2VjcmV0S2V5MQ==:CLIENT-A";

const maskedPassword = MaskData.maskPassword(password, maskPasswordOptions);
//Output: TESTXXXXXXX:CLIENT-A

maskPasswordOptions.unmaskedStartCharacters = 0;

const maskedPassword = MaskData.maskPassword(password, maskPasswordOptions);
//Output: XXXXXXXXXXX:CLIENT-A

Mask Phone Number

const MaskData = require('./maskdata');

const maskPhoneOptions = {
  // Character to mask the data
  // default value is '*'
  maskWith: "*",

  //Should be positive Integer
  // If the starting 'n' digits need to be unmasked
  // Default value is 4
  unmaskedStartDigits: 5, 

  // Should be positive Integer
  //If the ending 'n' digits need to be unmasked
  // Default value is 1
  unmaskedEndDigits: 1 
};

const phoneNumber = "+911234567890";

const maskedPhoneNumber = MaskData.maskPhone(phoneNumber, maskPhoneOptions);
//Output: +9112*******0

Mask Phone Number with the default configuration

To mask with the default options, don't pass the configurations.

const MaskData = require('./maskdata');

/** Default Options
  maskWith: "*"
  unmaskedStartDigits: 4
  unmaskedEndDigits: 1 
**/
const phoneNumber = "+111234567890";

const maskedPhoneNumber = MaskData.maskPhone(phoneNumber);

//Output: +911********0

Generic string masking

This functionality can be used to mask any string with the below configs.

Example1

const MaskData = require('./maskdata');

const defaultStringMaskV2Options = {
  // Character to mask the data
  // default value is '*'
  maskWith: "*",

  // This is to limit the maximun characters in the output.
  // Default value is 256
  maxMaskedCharacters: 256,

  // To fix the length of output irrespective of the length of the input. This comes in handy when the input length < maxMaskedCharacters but we want a fixed output length.
  // Default value is undefined. If this value is set, then maxMaskedCharacters will not be considered and the output length will always be equal to fixedOutputLength characters.
  fixedOutputLength: undefined,

  // To show(not mask) first 'n' characters of the string.
  // Default value is 0. 
  unmaskedStartCharacters: 0,

  // To show(not mask) last 'n' characters of the string.
  // Default value is 0. 
  unmaskedEndCharacters: 0
};

const string1 = "Password1$";

const maskedString = MaskData.maskStringV2(string1, defaultStringMaskV2Options);

//Output: **********

Example2

const MaskData = require('./maskdata');

const stringMaskV2Options = {
  maskWith: "X",
  maxMaskedCharacters: 20, // To limit the output length to 20.
  unmaskedStartCharacters: 4,
  unmaskedEndCharacters: 9,
  fixedOutputLength: undefined
};

const secret = "TEST:U2VjcmV0S2V5MQ==:CLIENT-A";

const maskedSecret = MaskData.maskStringV2(password, stringMaskV2Options);
//Output: TESTXXXXXXX:CLIENT-A

stringMaskV2Options.unmaskedStartCharacters = 0;

maskedSecret = MaskData.maskStringV2(password, stringMaskV2Options);
//Output: XXXXXXXXXXX:CLIENT-A

Mask the characters or words in the string

This will mask the characters or words if present in the given string.

const MaskData = require('./maskdata');

const maskStringOptions = {
  // Character to mask the data. The default value is '*'
  maskWith: "*",

  /** 
   * It is the words/substrings to mask. 
   * Should be an array of strings.
   * Can give multiple words/substrings.
   * values[] can be used only when maskAll is false. If maskAll is true, then this is of no use.
  */
  values: ['is', 'test'], 

  /** 
   * If to mask only the first occurrence of each word/substring in the given string
   * Should be boolean
   * Default value is false
  */
  maskOnlyFirstOccurance: false,

  /** 
   * If to mask all the characters in a string make maskAll: true
   * If maskAll is true, the words/substrings inside values[] will not be considered. 
   * Default value is false
  */
  maskAll: false,

  /** 
   * This is to mask/not mask the spaces in a string when masking all the characters.
   * Can be used ONLY when maskAll: true
   * If maskSpace is false, the spaces in the string will not be masked.
   * This feature is to know the words and each word's length but to hide the content
   * Default value is true
  */
  maskSpace: true
};

const str = "This is a test String";

const strAfterMasking = MaskData.maskString(str, maskStringOptions);

//Output: Th** ** a **** String

Mask all characters in the String

const str = "This is a test String";

const strAfterMasking = MaskData.maskString(str, maskStringOptions);

const stringMaskOptions = {
  maskWith: "*",
  values: [],
  maskAll: true,
  maskSpace: false   // Maks all characters except spaces
};

// Output: **** ** * **** *****

const str = "This is a test String";

const strAfterMasking = MaskData.maskString(str, maskStringOptions);

const stringMaskOptions = {
  maskWith: "*",
  values: [],
  maskAll: true,
  maskSpace: true   // Mask all characters including spaces
};

// Output: ********************

Mask UUID

This will mask the alphanumeric characters in a UUID.This will not mask the hyphen present in the UUID. Masking is done, only when the input is a valid UUID with only a-f, A-F, and 0-9 and has 36 characters (32 alphanumerics + 4 hyphens, and should work with the regex:

/[a-fA-F0-9]{8}-[a-fA-F0-9]{4}-[a-fA-F0-9]{4}-[a-fA-F0-9]{4}-[a-fA-F0-9]{12}/g;).

If the input is not a valid UUID, it will return the input itself without masking.

const MaskData = require('./maskdata');

const maskUuidOptions = {
  // Character to mask the data. The default value is '*'
  maskWith: "*",

  // Should be a positive Integer <= 32
  // If the starting 'n' alphanumeric characters need to be visible/unmasked
  // Default value is 0
  unmaskedStartCharacters: 0, 
  
  //Should be a positive Integer <= 32
  //If the ending 'n' alphanumeric characters need to be visible/unmasked
  // Default value is 0 
  unmaskedEndCharacters: 0
};

const uuidInput = "123e4567-e89b-12d3-a456-426614174000";

const uuidAfterMasking = MaskData.maskUuid(uuidInput, maskUuidOptions);

// Output: ********-****-****-****-************

Mask JWT Token

This function returns the masked JWT tokens. A JWT token consists of 3 parts separated by 2 dots. i.e, {header}.{payload}.{signature}. Based on the usecase, we will have to mask/keep a part/s of jwt token. With maskdata you can mask JWT tokens with all possible combinations. If the input is null, undefined, non-string, string with length < 5, doesn't contain 2 dots(invalid JWT format), the function will return the input as it is without masking.

const MaskData = require('./maskdata');

const jwtMaskOptions = {
  // Character to mask the data. The default value is '*'
  maskWith: '*',

  // Max masked characters in the output(EXCLUDING the unmasked characters). Default value is 512
  maxMaskedCharacters: 512,

  // Config to mask OR keep the dots(.). Default value is true, i.e, mask dots
  maskDot: true,

  // Config to mask OR keep the first part of the JWT. i.e, the header part. Default value is true, i.e, mask the header part
  maskHeader: true,

  // Config to mask OR keep the second part of the JWT. i.e, the payload part. Default value is true, i.e, mask the payload part
  maskPayload: true,

  // Config to mask OR keep the third part of the JWT. i.e, the signature part. Default value is true, i.e, mask the signature part
  maskSignature: true
};

const jwt =
  'eyJhbGciOiJIUzI1NiIsInR5cCI6IkpXVCJ9.eyJpYXQiOjE1MTYyMzkwMjJ9.tbDepxpstvGdW8TC3G8zg4B6rUYAOvfzdceoH48wgRQ';

/** In this example,
 * Header = eyJhbGciOiJIUzI1NiIsInR5cCI6IkpXVCJ9
 * Payload = eyJpYXQiOjE1MTYyMzkwMjJ9
 * Signature = tbDepxpstvGdW8TC3G8zg4B6rUYAOvfzdceoH48wgRQ
 */ 
const maskedJwt = MaskData.maskJwt(jwt, jwtMaskOptions);

// Output:
*********************************************************************************************************

Example: Mask only the signature part

const MaskData = require('./maskdata');

const jwtMaskOptions = {
  maskWith: '*',
  maxMaskedCharacters: 512,
  maskDot: false,
  maskHeader: false,
  maskPayload: false,
  maskSignature: true
};

const jwt =
  'eyJhbGciOiJIUzI1NiIsInR5cCI6IkpXVCJ9.eyJpYXQiOjE1MTYyMzkwMjJ9.tbDepxpstvGdW8TC3G8zg4B6rUYAOvfzdceoH48wgRQ';

/** In this example,
 * Header = eyJhbGciOiJIUzI1NiIsInR5cCI6IkpXVCJ9
 * Payload = eyJpYXQiOjE1MTYyMzkwMjJ9
 * Signature = tbDepxpstvGdW8TC3G8zg4B6rUYAOvfzdceoH48wgRQ
 */ 
const maskedJwt = MaskData.maskJwt(jwt, jwtMaskOptions);

// Output:
eyJhbGciOiJIUzI1NiIsInR5cCI6IkpXVCJ9.eyJpYXQiOjE1MTYyMzkwMjJ9.*******************************************

Example: Mask header and the signature part

const MaskData = require('./maskdata');

const jwtMaskOptions = {
  maskWith: '*',
  maxMaskedCharacters: 512,
  maskDot: false,
  maskHeader: true,
  maskPayload: false,
  maskSignature: true
};

const jwt =
  'eyJhbGciOiJIUzI1NiIsInR5cCI6IkpXVCJ9.eyJpYXQiOjE1MTYyMzkwMjJ9.tbDepxpstvGdW8TC3G8zg4B6rUYAOvfzdceoH48wgRQ';

/** In this example,
 * Header = eyJhbGciOiJIUzI1NiIsInR5cCI6IkpXVCJ9
 * Payload = eyJpYXQiOjE1MTYyMzkwMjJ9
 * Signature = tbDepxpstvGdW8TC3G8zg4B6rUYAOvfzdceoH48wgRQ
 */ 
const maskedJwt = MaskData.maskJwt(jwt, jwtMaskOptions);

// Output:
************************************.eyJpYXQiOjE1MTYyMzkwMjJ9.*******************************************

Example: Mask all parts except dots and limit the max masked characters in the output to lower value, say 16

const MaskData = require('./maskdata');

const jwtMaskOptions = {
  maskWith: '*',
  maxMaskedCharacters: 16,
  maskDot: false,
  maskHeader: true,
  maskPayload: true,
  maskSignature: true
};

const jwt =
  'eyJhbGciOiJIUzI1NiIsInR5cCI6IkpXVCJ9.eyJpYXQiOjE1MTYyMzkwMjJ9.tbDepxpstvGdW8TC3G8zg4B6rUYAOvfzdceoH48wgRQ';

/** In this example,
 * Header = eyJhbGciOiJIUzI1NiIsInR5cCI6IkpXVCJ9
 * Payload = eyJpYXQiOjE1MTYyMzkwMjJ9
 * Signature = tbDepxpstvGdW8TC3G8zg4B6rUYAOvfzdceoH48wgRQ
 */ 
const maskedJwt = MaskData.maskJwt(jwt, jwtMaskOptions);

// Output:
******.*****.*****

Mask JSON

This is the functionality in version 1.2.0+ to handle masking of multiple types of data in a JSON with a single function call.

const MaskData = require('./maskdata');

// Default configs are as below. If specific masking changes are needed, use the corresponding configs for each type of field.
const defaultjsonMask2Configs = {
    cardMaskOptions: defaultCardMaskOptions, // Optional 
    cardFields: [], // List of card fields to be masked

    emailMaskOptions: defaultEmailMask2Options, // Optional 
    emailFields: [], // List of email fields to be masked

    passwordMaskOptions: defaultPasswordMaskOptions, // Optional 
    passwordFields: [], // List of password fields to be masked

    phoneMaskOptions: defaultPhoneMaskOptions, // Optional 
    phoneFields: [], // List of phone fields to be masked

    stringMaskOptions:  defaultStringMaskOptions, // Mandatory if stringFields are given. Otherwise, stringFields won't be masked
    stringFields: [], // List of String fields to be masked

    uuidMaskOptions: defaultUuidMaskOptions, // Optional 
    uuidFields: [], // List of UUID fields to be masked

    jwtMaskOptions: defaultJwtMaskOptions, // Optional 
    jwtFields: [], // List of JWT fields to be masked

    genericStrings: [ // This list can have multiple entries of { config: defaultStringMaskV2Options, fields: [] }
      {
        config: defaultStringMaskV2Options,
        fields: []
      }
    ]
};

NOTE: For details on the configs mentioned above, refer: defaultCardMaskOptionsdefaultEmailMask2Options defaultPasswordMaskOptions defaultPhoneMaskOptions defaultStringMaskOptions defaultUuidMaskOptions defaultJwtMaskOptions defaultStringMaskV2Options / generic String Maksing

const defaultjsonMask2Configs = {
    cardMaskOptions: {
        maskWith: "*",
        unmaskedStartDigits: 4,
        unmaskedEndDigits: 1
    },
    cardFields: [],

    emailMaskOptions: {
        maskWith: "*",
        unmaskedStartCharactersBeforeAt: 3,
        unmaskedEndCharactersAfterAt: 2,
        maskAtTheRate: false
    },
    emailFields: [],

    passwordMaskOptions: {
        maskWith: "*",
        maxMaskedCharacters: 16,
        fixedOutputLength: undefined,
        unmaskedStartCharacters: 0,
        unmaskedEndCharacters: 0
    },
    passwordFields: [],

    phoneMaskOptions: {
        maskWith: "*",
        unmaskedStartDigits: 4,
        unmaskedEndDigits: 1
    },
    phoneFields: [],

    stringMaskOptions:  {
        maskWith: "*",
        maskOnlyFirstOccurance: false,
        values: [],
        maskAll: false,
        maskSpace: true
    },
    stringFields: [],

    uuidMaskOptions: {
        maskWith: "*",
        unmaskedStartCharacters: 0,
        unmaskedEndCharacters: 0
    },
    uuidFields: [],

    jwtMaskOptions: {
        maskWith: '*',
        maxMaskedCharacters: 512,
        maskDot: true,
        maskHeader: true,
        maskPayload: true,
        maskSignature: true
    },
    jwtFields: [],
    // To extend the mask function to generic strings. 
    genericStrings: [
      {
        config: {
          maskWith: "*",
          maxMaskedCharacters: 256,
          fixedOutputLength: undefined,
          unmaskedStartDigits: 0,
          unmaskedEndDigits: 0
        },
        fields: []
      }
    ]
};

JSON mask examples

Example1:

const jsonInput = {
  'credit': '1234-5678-8765-1234', 
  'debit': '0000-1111-2222-3333', 
  'primaryEmail': '[email protected]', 
  'secondaryEmail': '[email protected]',
  'password': 'dummyPassword',
  'homePhone': "+1 1234567890",
  'workPhone': "+1 9876543210",
  'addressLine1': "This is my addressline 1. This is my home",
  'addressLine2': "AddressLine 2",
  'uuid1': '123e4567-e89b-12d3-a456-426614174000',
  'randomStrings': {
    'row1': 'This is row 1 random string',
    'row2': ['Entry1', 'Entry2', 'Entry3'],
    'row3': {
      'key1': 'Row3 Object 1',
      'key2': 'Row3 Object 2',
      'key3': ['Entry1', 'Entry2', 'Entry3']
    }
  }
};

const jsonMaskConfig = {
    cardFields: ['credit', 'debit'],
    emailFields: ['primaryEmail', 'secondaryEmail'],
    passwordFields: ['password'],
    phoneFields: ['homePhone', 'workPhone'],
    stringMaskOptions:  {
      maskWith: "*",
      maskOnlyFirstOccurance: false,
      values: ["This"]
    },
    stringFields: ['addressLine1', 'addressLine2'],
    uuidFields: ['uuid1'],
    genericStrings: [
        {
          fields: ['randomStrings.row1'],
          config: {
            maskWith: '*',
            unmaskedStartCharacters: 2,
            unmaskedEndCharacters: 3,
            maxMaskedCharacters: 8
          }
        },
        { fields: ['randomStrings.row2.*'], config: { maskWith: 'X', unmaskedEndCharacters: 1 } },
        { fields: ['randomStrings.row3.key1'] },
        {
          fields: ['randomStrings.row3.key3.*'],
          config: { maskWith: '@', unmaskedEndCharacters: 1 }
        }
    ]
};

const maskedJsonOutput = maskData.maskJSON2(jsonInput, jsonMaskConfig);

Output:
{
  credit: '1234-****-****-***4',
  debit: '0000-****-****-***3',
  primaryEmail: 'pri****@*******om',
  secondaryEmail: 'sec******@*******om',
  password: '*************',
  homePhone: '+1 1********0',
  workPhone: '+1 9********0',
  addressLine1: '**** is my addressline 1. **** is my home',
  addressLine2: 'AddressLine 2',
  uuid1: '********-****-****-****-************',
  randomStrings: {
    row1: 'Th***ing',
    row2: ['XXXXX1', 'XXXXX2', 'XXXXX3'],
    row3: {
      key1: '*************',
      key2: 'Row3 Object 2',
      key3: ['@@@@@1', '@@@@@2', '@@@@@3']
    }
  }
}


Example2: Mask with custom configs for each/any type of fields

const jsonInput2 = {
  'credit': '1234-5678-8765-1234', 
  'debit': '0000-1111-2222-3333', 
  'primaryEmail': '[email protected]', 
  'secondaryEmail': '[email protected]',
  'password': 'dummyPasswordANDdummyPassword',
  'homePhone': "+1 1234567890",
  'workPhone': "+1 9876543210",
  'addressLine1': "This is my addressline 1. This is my home",
  'addressLine2': "AddressLine 2",
  'uuid1': '123e4567-e89b-12d3-a456-426614174000'
};

const jsonMaskConfig2 = {
    // Card
    cardMaskOptions: { maskWith: "X", unmaskedStartDigits: 2,unmaskedEndDigits: 4 },
    cardFields: ['credit', 'debit'],

    // Email
    emailMaskOptions: { maskWith: "*", unmaskedStartCharactersBeforeAt: 2, unmaskedEndCharactersAfterAt: 2, maskAtTheRate: false },
    emailFields: ['primaryEmail', 'secondaryEmail'],

    // Password
    passwordMaskOptions: { maskWith: "*", maxMaskedCharacters: 10, unmaskedStartCharacters: 0, unmaskedEndCharacters: 0 },
    passwordFields: ['password'],

    // Phone
    phoneMaskOptions: { maskWith: "*", unmaskedStartDigits: 2, unmaskedEndDigits: 1 },
    phoneFields: ['homePhone', 'workPhone'],

    // String
    stringMaskOptions: { maskWith: "*", maskOnlyFirstOccurance: false, values: [], maskAll: true, maskSpace: false },
    stringFields: ['addressLine1', 'addressLine2'],

    // UUID
    uuidMaskOptions: { maskWith: "*", unmaskedStartCharacters: 4, unmaskedEndCharacters: 2 },
    uuidFields: ['uuid1']
};

const maskedJsonOutput2 = maskData.maskJSON2(jsonInput2, jsonMaskConfig2);

Output:

{
  credit: '12XX-XXXX-XXXX-1234',
  debit: '00XX-XXXX-XXXX-3333',
  primaryEmail: 'pr*****@*******om',
  secondaryEmail: 'se*******@*******om',
  password: '**********',
  homePhone: '+1**********0',
  workPhone: '+1**********0',
  addressLine1: '**** ** ** *********** ** **** ** ** ****',
  addressLine2: '*********** *',
  uuid1: '123e****-****-****-****-**********00'
}

Example3: Mask nested json fields -> Use dot(.) and Array([]) notation to specify the inner fields.

const jsonInput2 = {
  cards: {
    creditCards: ['1234-5678-8765-1234', '1111-2222-1111-2222'],
    debitCards: ['0000-1111-2222-3333', '2222-1111-3333-4444']
  },
  emails: {
    primaryEmail: '[email protected]', 
    secondaryEmail: '[email protected]'
  },
  passwords: [
    ['dummyPasswordANDdummyPassword', 'dummyPasswordANDdummyPassword']
  ],
  phones: {
    homePhone: "+1 1234567890",
    workPhone: "+1 9876543210",
  },
  address: {
    addressLine1: "This is my addressline 1. This is my home",
    addressLine2: "AddressLine 2"
  },
  uuids: {
    uuid1: '123e4567-e89b-12d3-a456-426614174000'
  },
  jwt: 'eyJhbGciOiJIUzI1NiIsInR5cCI6IkpXVCJ9.eyJpYXQiOjE1MTYyMzkwMjJ9.tbDepxpstvGdW8TC3G8zg4B6rUYAOvfzdceoH48wgRQ'
};

const jsonMaskConfig2 = {
    // Card
    cardMaskOptions: { maskWith: "X", unmaskedStartDigits: 2,unmaskedEndDigits: 4 },
    cardFields: ['cards.creditCards[0]', 'cards.creditCards[1]', 'cards.debitCards[0]', 'cards.debitCards[1]'],

    // Email
    emailMaskOptions: { maskWith: "*", unmaskedStartCharactersBeforeAt: 2, unmaskedEndCharactersAfterAt: 2, maskAtTheRate: false },
    emailFields: ['emails.primaryEmail', 'emails.secondaryEmail'],

    // Password
    passwordMaskOptions: { maskWith: "*", maxMaskedCharacters: 10, unmaskedStartCharacters: 0, unmaskedEndCharacters: 0 },
    passwordFields: ['passwords[0][0]]', 'passwords[0][1]'],

    // Phone
    phoneMaskOptions: { maskWith: "*", unmaskedStartDigits: 2, unmaskedEndDigits: 1 },
    phoneFields: ['phones.homePhone', 'phones.workPhone'],

    // String
    stringMaskOptions: { maskWith: "*", maskOnlyFirstOccurance: false, values: [], maskAll: true, maskSpace: false },
    stringFields: ['address.addressLine1', 'address.addressLine2'],

    // UUID
    uuidMaskOptions: { maskWith: "*", unmaskedStartCharacters: 4, unmaskedEndCharacters: 2 },
    uuidFields: ['uuids.uuid1']

    // JWT
    jwtMaskOptions: { maskWith: '*', maxMaskedCharacters: 512, maskDot: true, maskHeader: true, maskPayload: true, maskSignature: true},
    jwtFields: ['jwt']
};

const maskedJsonOutput2 = MaskData.maskJSON2(jsonInput2, jsonMaskConfig2);
// OUTPUT:
{
  cards: {
    creditCards: [ '12XX-XXXX-XXXX-1234', '11XX-XXXX-XXXX-2222' ],
    debitCards: [ '00XX-XXXX-XXXX-3333', '22XX-XXXX-XXXX-4444' ]
  },
  emails: {
    primaryEmail: 'pr*****@*******om',
    secondaryEmail: 'se*******@*******om'
  },
  passwords: [ [ '**********', '**********' ] ],
  phones: { homePhone: '+1**********0', workPhone: '+1**********0' },
  address: {
    addressLine1: '**** ** ** *********** ** **** ** ** ****',
    addressLine2: '*********** *'
  },
  uuids: { uuid1: '123e****-****-****-****-**********00' },
  jwt: '*********************************************************************************************************'
}

Mask Multiple Fields

const jsonInput = {
  cards: [
    {
      number: '1234-5678-8765-1234'
    },
    {
      number: '1111-2222-1111-2222'
    },
    {
      number: '0000-1111-2222-3333'
    },
    {
      name: "No card number here"
    }
  ],
  emails: {
    primaryEmail: '[email protected]', 
    secondaryEmail: '[email protected]',
    moreEmails: ["[email protected]", "[email protected]", "[email protected]", {childEmail: "[email protected]", secondChild: {nestedkid: "[email protected]"}}]
  },
  array: ["element1", "element22", "element333"],
  jwt: 'eyJhbGciOiJIUzI1NiIsInR5cCI6IkpXVCJ9.eyJzdWIiOiJsb2wiLCJuYW1lIjoiVGVzdCIsImlhdCI6ImxvbCJ9.XNDxZcBWWEKYkCiu6XFGmAeuPF7iFnI7Sdv91gVZJMU'
};

const jsonMaskConfig = {
  cardMaskOptions: { maskWith: "X", unmaskedStartDigits: 0, unmaskedEndDigits: 0},

  emailMaskOptions: { maskWith: "*", unmaskedStartCharactersBeforeAt: 0, 
  unmaskedEndCharactersAfterAt: 0, maskAtTheRate: false },

  stringMaskOptions: { maskWith: "?", maskOnlyFirstOccurance: false, values: [], maskAll: true, maskSpace: false },
  jwtMaskOptions: { maskWith: '*', maxMaskedCharacters: 32, maskDot: false, maskHeader: true, maskPayload: true, maskSignature: true},

  cardFields: ['cards[*].number'],
  emailFields: ['emails.*'],
  stringFields: ['array.*'],
  jwtFields: ['jwt']
}

const maskedOutput = maskData.maskJSON2(jsonInput, jsonMaskConfig);

// Output: 
{
  "cards": [
    {
      "number": "XXXX-XXXX-XXXX-XXXX"
    },
    {
      "number": "XXXX-XXXX-XXXX-XXXX"
    },
    {
      "number": "XXXX-XXXX-XXXX-XXXX"
    },
    {
      "name": "No card number here"
    }
  ],
  "emails": {
    "primaryEmail": "*******@*********",
    "secondaryEmail": "*********@*********",
    "moreEmails": [
      "******@*********",
      "******@*********",
      "******@*********",
      {
        "childEmail": "*****@*********",
        "secondChild": {
          "nestedkid": "*****@*********"
        }
      }
    ]
  },
  "array": ["????????", "?????????", "??????????"],
  "jwt": "************.**********.**********"
}

Recursive Masking

If you want to mask all the fields with a name irrespective of its level in the json, use the *{field_name}.

Example:

const inputJson = {
  car: "Mazda",
  addressLine1: "Mask me!",
  deeper: {
    addressLine1: "Mask me!",
    evenDeeper: { addressLine1: "Mask me!" },
  },
};

const fieldsToMask = ["*addressLine1"];  // Specify the field with a '*' at the beginning and NO dot(.) anywhere else in that field.

const jsonMaskConfig = {
  genericStrings: [
    {
      config: {
        maskWith: "*",
        maxMaskedCharacters: 6
      },
      fields: fieldsToMask
    },
  ],
};

const maskedOutput = maskData.maskJSON2(inputJson, jsonMaskConfig);

// Output: 
{
  car: 'Mazda',
  addressLine1: '******',
  deeper: { addressLine1: '******', evenDeeper: { addressLine1: '******' } }
}

Example 2: Using Recursive masking to mask card numbers in a json using mask card config. Recursive masking can be used to mask all types of data mentioned here

const inputJson = {
  cards: [
    {
      number: "1234-5678-0123-0000"
    },
    {
      number: "1111-2222-3333-4444"
    },
    {
      number: "2222-4444-6666-8888"
    },
    {
      number: "1111-3333-5555-7777"
    },
    {
      number: "0000-0000-0000-0000"
    }
  ]
};

const cardfieldsToMask = ["*number"];  // Specify the field with a '*' at the beginning and NO dot(.) anywhere else in that field.
    
const jsonMaskConfig = {
  cardMaskOptions: {
        maskWith: "*",
        unmaskedStartDigits: 4,
        unmaskedEndDigits: 1
    },
  cardFields: cardfieldsToMask, 
};

const maskedOutput = maskData.maskJSON2(jsonInput, jsonMaskConfig);

// Output: 
{
  cards: [
    { number: '1234-****-****-***0' },
    { number: '1111-****-****-***4' },
    { number: '2222-****-****-***8' },
    { number: '1111-****-****-***7' },
    { number: '0000-****-****-***0' }
  ]
}

Get Nested JSON Property

This method returns the value of the nested JSON property if it exists. Otherwise, it returns undefined

const MaskData = require('./maskdata');

const innerPropety = Maskdata.getInnerProperty(object, field);

Example: 

const nestedObject = {
  level1: {
    field1: "field1",
    level2: {
      field2: "field2",
      level3: {
        field3: "field3",
        field4: [ { Hello: "world" }, { Hello: "Newworld" }, "Just a String" ]
      }
    }
  },
  value1: "value"
};

const innerPropety = Maskdata.getInnerProperty(nestedObject, 'level1.level2.level3.field4[0].Hello');

Replace the value of a JSON field

To replace a value by keeping the type.

const input = {
  name: "John",
  age: 33,
  married: true
}

let afterReplacing = MaskData.replaceValue(input, 'age', 99);
afterReplacing = MaskData.replaceValue(input, 'married', false);

//Output: 
Before replacing: {"name":"John","age":33,"married":true}
After replacing: {"name":"John","age":99,"married":false}

Type of age: number
Type of married: boolean

Report Bugs

If there is any help needed with the library functionalities or if there is any bug/issue, please raise an issue in GitHub: https://github.com/Sumukha1496/maskdata/issues

Give a Star

You can give a star at: https://github.com/Sumukha1496/maskdata/stargazers

LICENSE - "MIT"

Licensed under MIT Licence

Copyright (c) 2019 Sumukha H S

Permission is hereby granted, free of charge, to any person obtaining a copy of this software and associated documentation files (the "Software"), to deal in the Software without restriction, including without limitation the rights to use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of the Software, and to permit persons to whom the Software is furnished to do so, subject to the following conditions:

The above copyright notice and this permission notice shall be included in all copies or substantial portions of the Software.

THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NON-INFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES, OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.