javascript OOP 面向对象编程

Pseudo-class declaration

原文地址：http://javascript.info/tutorial/pseudo-classical-pattern#pseudo-class-declaration 

A pseudo-class consists of the constructor function and methods.
For example, here’s the Animal pseudo-class with single method sit and two properties.

function Animal(name) {
  this.name = name
}

Animal.prototype = { 
  canWalk: true,
  sit: function() {
    this.canWalk = false
    alert(this.name + ' sits down.')
  }
}

var animal = new Animal('Pet') // (1)

alert(animal.canWalk) // true

animal.sit()             // (2)

alert(animal.canWalk) // false

　　

1. When new Animal(name) is called, the new object recieves __proto__ reference toAnimal.prototype, see that on the left part of the picture.
2. Method animal.sit changes animal.canWalk in the instance, so now this animal object can’t walk. But other animals still can.

The scheme for a pseudo-class:

• Methods and default properties are in prototype.
• Methods in prototype use this, which is the current object because the value of this only depend on the calling context, so animal.sit() would set this to animal.