JS关于原型

发表于 更新于 分类于

一、实例

1. new Person()在前

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Person.prototype.name = 'sunny';

function Person() {}

var person = new Person();

Person.prototype.name = 'cherry';

console.log(person.name);  //cherry

2. new Person()在后

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Person.prototype.name = 'sunny';

function Person() {}

Person.prototype.name = 'cherry';

var person = new Person();

console.log(person.name);   //cherry

3. 改变写法

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Person.prototype.name = 'sunny';

function Person() {
    //var this = {__proto__ : Person.prototype}
}

var person = new Person();

Person.prototype = {
    name : 'cherry'
}

console.log(person.name);  //sunny
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这样理解
var obj = {name : "a"};
var obj1 = obj;
obj = {name : "b"};

Person.prototype = {name : "a"};
__proto__ = Person.prototype;
Person.prototype = {name : "b"};

4. new Person最后执行

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Person.prototype.name = 'sunny';

function Person() {
    // var this = {__proto__ : Person.prototype}
}

Person.prototype = {
    name : 'cherry'
}

var person = new Person();

console.log(person.name);   //cherry

二、隐式添加

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Person.prototype.name = 'abc';
function Person() {
    // let this = Object.create(Person.prototype);
    // let this = {
    // 	__proto__ : Person.prototype
    // }
}

let person = new Person();

三、继承

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// 继承  

//1.圣杯模式
function inherit(Target, Origin) {
    function F() {}
    F.prototype = Origin.prototype;
    Target.prototype = new F();
    Target.prototype.constructor = Target;
    Target.prototype.uber = Origin.prototype;
}

// 2.雅虎写法  闭包
var inherit = (function () {
    var F = function () {}
    return function (Target, Origin) {
        F.prototype = Origin.prototype;
        Target.prototype = new F();
        Target.prototype.constructor = Target;
        Target.prototype.uber = Origin.prototype;
    }
}());

Father.prototype.lastName = "G";

function Father() {}
function Son() {}

inherit(Son, Father);

var son = new Son();
var father = new Father();