JavaScript Snippet – Function.prototype.chain()

The following is a function which returns the chainable version of a function:

Function.prototype.chain = function() {
  var me = this;
  return function() {
    var ret = me.apply(this, arguments);
    return ret === undefined ? this : ret;
  }
};

Here is an example of how to define a pseudo-class which uses this chaining method:

function Person(firstName, lastName) {
  this._firstName = firstName;
  this._lastName = lastName;
}

Person.prototype.firstName = (function(firstName) {
  if(firstName)
    this._firstName = firstName;
  else
    return this._firstName;
}).chain();

Person.prototype.lastName = (function(lastName) {
  if(lastName)
    this._lastName = lastName;
  else
    return this._lastName;
}).chain();

Person.prototype.fullName = function() {
  return this._firstName + " " + this._lastName;
};

Here is an example which shows that the chaining works as intended:

// Create my person object as "Kris East" and display this faulty name.
var author = new Person("Kris", "East");
alert(author.fullName());

// Prove that first name getter works:  Kris
alert(author.firstName());

// Fix my name and then display it:  Chris West
alert(author.lastName("West").firstName("Chris").fullName());

// Prove that last name getter works:  West
alert(author.lastName());