Javascript 继承

参考：
JavaScript高级程序设计(第3版)

• 原型链

function SuperType() {
  this.property = true;
}

SuperType.prototype.getSuperValue = function () {
  return this.property;
}

function Subtype() {
  this.subproperty = false;
}

// 继承了SuperType
SubType.prototype = new SuperType();

SubType.prototype.getSubValue = function() {
  return this.subproperty;
}

var instance = new SubType();
console.log(instance.getSuperValue) // true;

• 原型式继承

function object(o) {
  function F() {}
  F.prototype = o;
  return new F();
}

var person = {
  name: "Nicolars",
  friends: ["s", "c", "v"]
};

var A = object(person);
A.name = "G";
A.friends.push("r");

var B = object(person);
B.name = "L";
B.friends.push("f");

console.log(person.friends) // "s, c, v, r, f"

• 寄生式继承

function createAnother(origin) {
  var clone = object(origin);
  clone.sayHi = function() {
    console.log("HI");
}
  return clone;
}

var person = {
  name: "N",
  friends: ["s", "c", "v"]
};

var anotherPerson = createAnother(person);
anotherPerson.sayHi(); // HI

• 寄生组合式继承

function SuperType(name) {
  this.name = name;
  this.colors = ["red", "blue", "green"];
}

SuperType.prototype.sayName = function () {
  console.log(this.name);
}

function SubType(name, age) {
  SuperType.call(this. name); 
  this.age = age;
}

SubType.prototype = new SuperType();
SubType.prototype.constructor = SubType;
SubType.prototype.sayAge = function() {
  console.log(this.age);
}