Example of Builder Pattern using TypeScript

client.ts

import UserAccountBuilder from './useraccount/UserAccountBuilder'
import UserAccount from 'useraccount/UserAccount'

const user: UserAccount = new UserAccountBuilder()
  .withFirstName('Dwiferdio Seagal')
  .withLastName('Putra')
  .withUsername('seagalputra')
  .withPassword('password')
  .withEmail('seagalputra')
  .build()

UserAccount.ts

class UserAccount {
  private firstName: string
  private lastName: string
  private username: string
  private email: string
  private password: string

  constructor(
    firstName: string,
    lastName: string,
    username: string,
    email: string,
    password: string
  ) {
    this.firstName = firstName
    this.lastName = lastName
    this.username = username
    this.email = email
    this.password = password
  }
}

export default UserAccount

UserAccountBuilder.ts

import UserAccount from './UserAccount'

class UserAccountBuilder {
  private firstName: string = ''
  private lastName: string = ''
  private username: string = ''
  private email: string = ''
  private password: string = ''

  constructor() {}

  public withFirstName(firstName: string): UserAccountBuilder {
    this.firstName = firstName
    return this
  }

  public withLastName(lastName: string): UserAccountBuilder {
    this.lastName = lastName
    return this
  }

  public withUsername(username: string): UserAccountBuilder {
    this.username = username
    return this
  }

  public withEmail(email: string): UserAccountBuilder {
    this.email = email
    return this
  }

  public withPassword(password: string): UserAccountBuilder {
    this.password = password
    return this
  }

  public build(): UserAccount {
    return new UserAccount(
      this.firstName,
      this.lastName,
      this.username,
      this.email,
      this.password
    )
  }
}

export default UserAccountBuilder