js中7种继承的实现和优缺点

function Parent(){
    this.name = ‘kevin‘
}

Parent.prototype.getName = function(){
    console.log(this.name)
}

function Child(){

}
Child.prototype = new Parent()

var child = new Child()
console.log(child.name) //kevin

function Parent(name){
    this.name = name
}

function Child(name){
    Parent.call(this,name)
}

let child = new Child(‘Tom‘)
let child1 = new Child(‘Jack‘)
console.log(child.name) //Tom
console.log(child1.name) //Jack

function Parent(name){
    this.name = name
    this.color = [‘red‘,‘bule‘,‘green‘]
}

Parent.prototype.getName = function(){
    console.log(this,name)
}

function Child(name,age){
    this.age = age
    Parent.call(this,name)
}

Child.prototype = new Parent()
Child.prototype.constructor = Child
Child.prototype.getAge = function(){
    console.log(this.age)
}

let child = new Child(‘Tom‘,12)
console.log(child.name) //Tom
child.getAge()  //12
child.color.push(‘blcak‘)
console.log(child.color) //[‘red‘,‘bule‘,‘green‘,‘black‘]

let child1 = new Child(‘Jack‘,18)
console.log(child1.name) //Jack
child1.getAge()  //18
console.log(child1.color) //[‘red‘,‘bule‘,‘green‘]

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

//在ES5中有了新方法代替Object.created(o,{name:‘Ton‘等新属性})

let person = {
    name:‘Tom‘,
    color : [‘red‘,‘bule‘,‘green‘]
}

let person1 = Object.create(person)
let person2 = Object.create(person)

person1.name = ‘Jack‘
person1.color.push(‘black‘)
person2.name = ‘Kevin‘
person1.color.push(‘yellow‘)

console.log(person1.name)   //Jack
console.log(person2.name)   //Kevin
console.log(person1.color == person2.color)  //true

let person = {
    name:‘Tom‘,
    color : [‘red‘,‘bule‘,‘green‘]
}

function createAnother(o){ 
    let clone = create(o)
    clone.getName(){
        console.log(this.name)
    }
    return clone    //clone这个对象不仅有原型引用属性，还有自己的方法
}

let person1 = createAnother(person)
person1.getName() //Tom 

function Parent (name) {
  this.name = name;
  this.colors = [‘red‘, ‘blue‘, ‘green‘];
}
 
Parent.prototype.getName = function () {
  console.log(this.name)
}
 
function Child (name, age) {
  Parent.call(this, name);
  this.age = age;
}

function prototype(Child,Parent){ //获得父类型原型上的方法
    let prototype = object(Parent.prototype) //创建父类型原型的一个副本，相当于prototype.__proto__ = Parent.prototype
    prototype.constructor = Child
    Child.prototype = prototype
}

prototype(Child,Parent) //必须执行这个函数，才能进行给子类型原型写方法，顺序调转的话子类型原型会被重写
Child.prototype.getName = function(){
    console.log(this.name)
}

class Parent {
    constructor(name,age){
        this.name = name
        this.age = age
    }
    showName(){
        console.log(this.name);
    }
}

class Child extends Parent{
    constructor(name,age,sex){
        super(name,age)
        this.sex = sex
    }
    showSex(){
        console.log(this.sex);
    }
}
let parent = new Parent(‘Jack‘,30)
console.log(parent.name,parent.age);
let child = new Child(‘Tom‘,12,‘男‘)
console.log(child.name,child.age);
child.showName() //Tom
child.showSex() //男