Method Chaining

WHAT IS METHOD CHAINING

Method chaining is a common syntax in object-oriented programming for invoking multiple method calls. The class methods must return the current object using the this keyword.

METHOD CHAINING EXAMPLES

• Method chaining in Javascript

  function Client() {
      this.name = null;
      this.phone = null;
  }
  Client.prototype = {
      getName: function () {
          return this.name;
      },
      setName: function (value) {
          this.name = value;
          return this;
      },
      setPhone: function (value) {
          this.phone = value;
          return this;
      }
  };
  
  alert(new Client().setName('John Smith').setPhone('+1 (555) 123-4567').getName()); // prints John Smith

• Method chaining in jQuery

  $('ul')
      .find('a:eq(1)')
      .addClass('active')
      .text('Test')
      .css('color', 'red')
      .show();

• Method chaining in PHP

  <?php
  class Client {
      private $name;
      private $phone;
  
      public function setName($value) {
          $this->name = $value;
          return $this;
      }
  
      public function setPhone($value) {
          $this->phone = $value;
          return $this;
      }
  
      public function getName() {
          return $this->name;
      }
  }
  
  $client = new Client();
  echo $client->setName('Jane Doe')->setPhone('+1 (546) 854-9551')->getName(); // prints Jane Doe
  ?>

METHOD CHAINING AND ERROR HANDLING

Throwing errors or returning boolean values from a method could break the chain, so proper error handling is a must.

function Client() {
    this.error = null;
    this.email = null;
    this.birthday = null;
}
Client.prototype = {
    getError: function () {
        return this.error;
    },
    hasError: function () {
        return this.error !== null;
    },
    getInfo: function () {
        return ['Send a mail to ', this.email, ' at ', this.birthday].join('');
    },
    setBirthday: function (value) {
        if (!/^\d{4}-\d{2}-\d{2}$/.test(value)) {
            this.error = 'Invalid ISO date.';
            return this;
        }
        this.birthday = value;
        return this;
    },
    setEmail: function (value) {
        if (!/[A-Z0-9._%+-]+@[A-Z0-9.-]+\.[A-Z]{2,}/i.test(value)) {
            this.error = 'Invalid email address';
            return this;
        }
        this.email = value;
        return this;
    }
};

var client = new Client();
if (!client.setEmail('www.domain.com').setBirthday('1987-10-29').hasError()) {
    console.log(client.getInfo());
} else {
    console.log(client.getError());
}

CONCLUSION

Method chaining could be extremely useful when it comes to execution of multiple consecutive methods over a single object.