继承模式

1.传统形式 —— 原型链

Grade.prototype.lastName = "wang";
function Grade(){}
var grade = new Grade();

Father.prototype = grade;
function Father(){
    this.name = 'hehe';
}
var father = new Father();

Son.prototype = father;
function Son(){}
var son = new Son();

过多的继承了没用的属性

2.借用构造函数

function Person () {
    this.name = name;
    this.age = age;
    this.sex = sex;
}
function Student (name, age, sex, grade) {
    Person.call(this, name, age, sex);
    this.grade = grade;
}
var student = new Student();

不能继承借用构造函数的原型 每次构造函数都要多走一个函数

3.共享原型(复制)

Father.prototype.lastName = 'deng';
function Father () {
    
}
function Son () {

}
function inherit(Target, Origin){
    Target.prototype = Origin.prototype;
}
inherit(Son, Father);
var son = new Son();
var father = new Father();

不能随便改动自己的原型

4.圣杯模式

function inherit (Target, Origin) {
    function F () {};
    F.prototype = Origin.prototype;
    Target.prototype = new F();
    Target.prototype.constuctor = Target;  // 防止指向紊乱
    Target.prototype.uber = Origin.prototype;  // 寻找自己的超类
}
Father.prototype.lastName = 'deng';
function Father(){};
function Son(){};
inherit(Son, Father);
var son = new Son();
var father = new Father();

雅虎封装 inherit 方法

var inherit = (function () {
    var F = function () {};
    return function (Target, Origin) {
        F.prototype = Origin.prototype;
        Target.prototype = new F();
        Target.prototype.constuctor = Target;  // 防止指向紊乱
        Target.prototype.uber = Origin.prototype;  // 寻找自己的超类
    }
}());