@password-validator/core

---

A zero dependency library for password validation that lets you compose and combine multiple rules to create a validator that suits your needs.

Installation

npm install @password-validator/core

Basic Usage

import { LowerCaseValidator, MaxLengthValidator, MinLengthValidator, PasswordValidatorManager, SpecialCharacterValidator, UpperCaseValidator } from '@password-validator/core';

const pm = new PasswordValidatorManager(); // Create a password validator manager

const minLength = new MinLengthValidator(8); // Minimum length of 8 characters
const maxLength = new MaxLengthValidator(16); // Maximum length of 16 characters
const uppercases = new UpperCaseValidator(2); // At least 2 uppercase characters
const lowercases = new LowerCaseValidator(2); // At least 2 lowercase characters
const specialCharacters = new SpecialCharacterValidator(2); // At least 2 special characters

// Register all the validators with the manager
pm.register(minLength, maxLength, uppercases, lowercases, specialCharacters);

// Use the manager to validate passwords
const result = pm.validate('MyPassword123!*') // { valid: true, messages: [] } --> Password is valid
const result = pm.validate('MyPassword123'); // { valid: false, messages: ['must contain at least 2 special characters.'] } --> Password is invalid

Validators

A validator is class that can validate a password and return a result. Validators should typically be registered with the PasswordValidatorManager (as shown above). The library comes with a number of validators (see table below) that can be used to build a validation suite.

Each validator receives a passwordRule (number) argument in its constructor which defines the number of expected characters associated with the validator. For example, the const minLength = new MinLengthValidator(10) defined above means that the passowrd must be atleast 10 characters long to be considered valid.

NB: The only exception to this is the NoSpaceCharacterValidator which requires no arguments and simply ensures the password contains no spaces.

Conflicting Validators

In a case of conflict validations, for example, a password must be 12 characters long minimum, and also be 8 characters maximum, we throw a PasswordValidatorConflictException error. This is because minimum length cannot be greater than maximum length.

import { MinLengthValidator, MaxLengthValidator } from '@password-validator/core';

const pm = new PasswordValidatorManager(); // Create a password validator manager

const minLength = new MinLengthValidator(12);
const maxLength = new MaxLengthValidator(8);

pm.register(minLength, maxLength);

const result = pm.validate('MyPassword123!*') // Throws PasswordValidatorConflictException --> `minLength cannot be greater than maxLength`

Validators & Managers Tables

Supported Validators and Managers as of now are:

Rules	Descriptions
Validations
DigitValidator(passwordRule: number)	specifies password must include passwordRule number of digits
LowerCaseValidator(passwordRule: number)	specifies password must include at least passwordRule number of lowercase character(s)
UpperCaseValidator(passwordRule: number)	specifies password must include at least passwordRule number of uppercase character(s)
MaxLengthValidator(passwordRule: number)	specifies password must not exceed passwordRule number of character(s)
MinLengthValidator(passwordRule: number)	specifies password must not be less than passwordRule number of character(s)
SpecialCharacterValidator(passwordRule: number)	specifies password must include at least passwordRule number of special character(s)
NoSpaceCharacterValidator()	specifies password must not include spaces
Managers
PasswordValidatorManager().register(...validators: PasswordValidator[])	Register multiple validators at once to build a validation suite.