Value Object implementation pattern

emailaddress.js

const emailAddress = (address) => {
  let _address = address;
  
    /**
     * @todo put validation
     **/
  
  let email = Object.assign({}, {
    valueOf() {
      return _address;
    },
    address() {
      return _address;
    },
    toString() {
      return _address;
    },
    equals(other) {
      return this.address() === other.address();
    }
  })
  
  
  return Object.freeze(email);
}

EmailAddress.php

<?php

class EmailAddress
{
  /**
   * Undocumented variable
   *
   * @var [type]
   */
  private $address;

  /**
   * Undocumented function
   *
   * @param [type] $address
   */
  private function __construct($address)
  {
    $this->setAddress($address);
  }

  /**
   * Undocumented function
   *
   * @param [type] $address
   * @return void
   */
  public static function fromString($address)
  {
    return new self($address);
  }

  /**
   * Undocumented function
   *
   * @return void
   */
  public function address()
  {
    return $this->address;
  }

  /**
   * Undocumented function
   *
   * @return string
   */
  public function __toString()
  {
    return $this->address();
  }

  /**
   * Undocumented function
   *
   * @param [type] $address
   * @return void
   */
  private function setAddress($address)
  {
    if (false == Assertion::email($email)) {
      throw new \Exception('Invalid email address');
    }
    $this->address = $address;
  }
}