細(xì)節(jié)：js 對(duì)象繼承的幾種模式舉例

Backache 發(fā)布于2019-08-21 10:49 / 437人閱讀

摘要：原型鏈繼承借用構(gòu)造函數(shù)偽造對(duì)象，經(jīng)典繼承無(wú)參數(shù)有參數(shù)組合繼承偽經(jīng)典繼承無(wú)參數(shù)有參數(shù)寄生組合式繼承引用類(lèi)型最理想的范式或者可以把函數(shù)寫(xiě)成下面這樣原型式繼承用于共享引用類(lèi)型的值，與寄生式類(lèi)似傳統(tǒng)版先定義函數(shù)，再繼承版直接用，再繼承省略了定義函數(shù)

原型鏈繼承

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());

借用構(gòu)造函數(shù)（偽造對(duì)象，經(jīng)典繼承） 無(wú)參數(shù)

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"]

有參數(shù)

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

組合繼承（偽經(jīng)典繼承） 無(wú)參數(shù)

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

有參數(shù)

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

寄生組合式繼承（引用類(lèi)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 函數(shù)寫(xiě)成下面這樣：

function inheritPrototype(SubType,SuperType){
    SubType.prototype = new SuperType();
    SubType.prototype.constructor = SubType;
}

原型式繼承（用于共享引用類(lèi)型的值，與寄生式類(lèi)似） 傳統(tǒng)版（先定義object() 函數(shù)，再繼承）

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()，再繼承）

var SuperType = {
    name: "Oliver",
    number: [321,321,4532,1]
};

var SubType1 = Object.create(SuperType); //省略了定義object()函數(shù)
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 簡(jiǎn)寫(xiě)版（定義Object.create()的第二個(gè)參數(shù)，再繼承）

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

寄生式繼承（用于共享引用類(lèi)型的值，與原型式類(lèi)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