理解js对象继承的N种模式

本文分享了js对象继承的N种模式，供大家参考。

一、原型链继承

function Person(){};

Person.prototype = {

constructor: Person,

name: "Oliver"

};

function People(){};

People.prototype = new Person();

People.prototype.constructor = People;

People.prototype.sayName = function(){

return this.name;

};

var ins = new People();

console.log(ins.sayName());

二、借用构造函数（伪造对象，经典继承）

1、无参数

function SuperType(){

this.color = ["red","yellow","white"];

}

function SubType(){

SuperType.call(this);

}

var instance1 = new SubType();

var instance2 = new SubType();

instance1.color.pop();

console.log(instance1.color); //["red", "yellow"]

console.log(instance2.color); //["red", "yellow", "white"]

2、有参数

function SuperType(name){

this.name = name;

this.number = [21,32,14,1];

}

function SubType(name,age){

SuperType.call(this,name);

this.age = age;

}

var instance1 = new SubType("Oliver",18);

var instance2 = new SubType("Troy",24);

instance2.number.pop();

console.log(instance1.name + instance1.age + instance1.number); //Oliver1821,32,14,1

console.log(instance2.name + instance2.age + instance2.number); //Troy2421,32,14

三、组合继承（伪经典继承）

1、无参数

function SuperType(){

this.color = ["red","yellow","white"];

}

SuperType.prototype.sayColor = function(){

return this.color;

};

function SubType(){

SuperType.call(this);

this.number = 321;

}

SubType.prototype = new SuperType();

SubType.prototype.constructor = SubType;

SubType.prototype.sayNumber = function(){

return this.number;

};

var instance1 = new SubType();

var instance2 = new SubType();

instance2.color.pop();

console.log(instance1.color + instance1.number); //red,yellow,white321

console.log(instance2.color + instance2.number); //red,yellow321

2、有参数

function SuperType(name){

this.name = name;

this.number = [32,1342,11,1];

}

SuperType.prototype.sayName = function(){

return 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(){

return this.age;

};

var instance1 = new SubType("Oliver",18);

var instance2 = new SubType("Troy",24);

instance2.number.pop();

console.log(instance1.sayName() + instance1.sayAge() + instance1.number); //Oliver1832,1342,11,1

console.log(instance2.sayName() + instance2.sayAge() + instance2.number); //Troy2432,1342,11

三、寄生组合式继承（引用类型最理想的范式）

function inheritPrototype(subType,superType){

var prototype = Object(superType.prototype);

prototype.constructor = subType;

subType.prototype = prototype;

}

function SuperType(name){

this.name = name;

this.number = [321,321,43];

}

SuperType.prototype.sayName = function(){

return this.name;

};

function SubType(name,age){

SuperType.call(this,name);

this.age = age;

}

inheritPrototype(SubType,SuperType);

SubType.prototype.sayAge = function(){

return this.age;

};

var instance1 = new SubType("Oliver",18);

var instance2 = new SubType("Troy",24);

instance2.number.pop();

console.log(instance1.sayName() + instance1.sayAge() + instance1.number); //Oliver18321,321,43

console.log(instance2.sayName() + instance2.sayAge() + instance2.number); //Troy24321,321

或者可以把inheritPrototype 函数写成下面这样：

function inheritPrototype(SubType,SuperType){

SubType.prototype = new SuperType();

SubType.prototype.constructor = SubType;

}

四、原型式继承（用于共享引用类型的值，与寄生式类似）

1、传统版（先定义object() 函数，再继承）

function object(o){

function F(){};

F.prototype = o;

return new F();

}

var SuperType = {

name: "Oliver",

number: [321,321,4532,1]

};

var SubType1 = object(SuperType);

var SubType2 = object(SuperType);

SubType1.name = "Troy";

SubType1.number.pop();

SubType2.name = "Alice";

SubType2.number.pop();

console.log(SubType1.name + SubType2.name + SubType1.number + SubType2.number + SuperType.name + SuperType.number); //TroyAlice321,321321,321Oliver321,321

ECMAScript 5 版（直接用Object.create()，再继承）

var SuperType = {

name: "Oliver",

number: [321,321,4532,1]

};

var SubType1 = Object.create(SuperType); //省略了定义object()函数

var SubType2 = Object.create(SuperType);

SubType1.name = "Troy";

SubType1.number.pop();

SubType2.name = "Alice";

SubType2.number.pop();

console.log(SubType1.name + SubType2.name + SubType1.number + SubType2.number + SuperType.name + SuperType.number); //TroyAlice321,321321,321Oliver321,321

ECMAScript 5 简写版（定义Object.create()的第二个参数，再继承）

var SuperType = {

name: "Oliver",

number: [321,321,4532,1]

};

var SubType1 = Object.create(SuperType,{

name: {

value : "Troy"

}

});

var SubType2 = Object.create(SuperType,{

name: {

value : "Alice"

}

});

SubType1.number.pop();

SubType2.number.pop();

console.log(SubType1.name + SubType2.name + SubType1.number + SubType2.number + SuperType.name + SuperType.number); //TroyAlice321,321321,321Oliver321,321

寄生式继承（用于共享引用类型的值，与原型式类似）

function createAnother(original){

var clone = Object(original);

clone.sayHi = function(){

return "Hi";

};

return clone;

}

var person = {

name: "Oliver",

number: [13,21,31,1]

};

var anotherPerson = createAnother(person);

anotherPerson.number.pop();

console.log(anotherPerson.sayHi() + anotherPerson.number); //Hi13,21,31

console.log(person.number); //13,21,31

以上就是本文的全部内容，希望对大家的学习有所帮助。