1.class简单应用

//传统对象 - function
function Course(teacher,course){
	this.teacher=teacher;
	this.course=course;
}
Course.prototype.getCourse=function(){
	return `teacher is ${this.teacher},course:${this.course}`
}

const course=new Course('aa','ES6');
course.getCourse()

//Es6
class Course{
 constructor(teacher,course){
	this.teacher=teacher;
	this.course=course;
  }
  //拓展方法
  getCourse(){
   return `teacher is: ${this.teacher},course is ${this.course}`
 }
}

const course =new Course('aa','ES6');
course.getCourse()

2.class的类型

console.log(typeOf course)  //function

3.class的prototype

// 有区分，但本质类型相同
 function Course(teacher, course) {
        this.teacher = teacher;
        this.course = course;
    }
    
class Course1 {
        // init 实例会默认执行
        constructor(teacher, course) {
            this.teacher = teacher;
            this.course = course;
        }

        // 拓展方法
        getCourse() {
            return `teacher is:${this.teacher}, course: ${this.course}`;
        }
    }

4.class & 函数对象 属性

console.log(course.hasOwnProperty('teacher')); // true

5.属性定义 构造器 & 顶层定义 两种定义方式

class Course {
// init 实例会默认执行
 constructor(teacher,course){
 this.teacher=teacher;
 this.course=course;
 }

//拓展方法
getCourse(){
  return `teacher is : ${this.teacher},course is : $ {this.course}`
 }

 get teacher(){
 //留有空间
  return this.teacher
 }

 set teacher(val){
 //留有空间
 this.teacher=val
 }
}


//意义何在?
//1. js如何建立只读变量
class Course{
 //init 实例会默认执行
 constructor(teacher,course){
  this._teacher=teacher;
  this.course=course;
 }
 //拓展方法
 getCourse(){
 return `teacher is :${this.teacher},course is :${this.course}`
 }
 
 get teacher(){
 //留有空间
 return this._teacher
 }
}

//修改只读变量，会报错么 - 无法改变但是不会报错

2.如何建立一个私有属性
class Course{
 constructor(){
 this._teacher=teacher;
 
 //在constrctor作用域内定义一个局部变量
 let _course = 'es6';
 //内部通过闭包的形式去暴露该变量
  this.getCourse=()=>{
     return this._course;
    }
  }
}

class Course{
 #course = 'es6';
 constructor(teacher,course){
  this._teacher = teacher;
 }
 get course(){
  return this.#course;
  }
 set course(val){
   if(val){
    this.#course = val
   }
 }
}

//3.封装核心 - 适配器模式
// 底层封装中台业务 core
class utils{
 constructor(core){
 this._main=core;
 this._name='my-utils';
 this._id='123'
 }
 
 //fullName:{firstName:" ",lastName:'',name:''}
  get name(){
  return {
  ...this._main.fullName,
  ...{
   name: `utils is ${this.name}`
    }
   }
   }
   get id(){
   return{
   ...this._main.id,
   id:this._id
   }
  }
  set name(val){
  //valid saftey
  this._name=val;
  }
}

6.静态方法 - 直接挂载在类上的方法无需实例化获取(static)

//es5实现
function Course(){
 // ...
} 
Course.ring=function(){
 //...
}

//es6实现
 class Course{
 constructor(){
 //...
 }
  static ring(){
  //...
  }
 }
Course.ring();
 //同一个class 多个实例，用于全局对象变量问题

7.继承

function Course(){
//...
}
//不用实例化可以调用 Course.ring()
Course.ring = function(){
 //...
 }
 //实例化后才可以调用
 Course.prototype.send=function(){
 //...
  }
   
 function Child(){
   Course.call(this,'aa','es6')
   this..run=function(){
   //...}
   }
   Child.prototype=Course.prototype;

//es6

class Course {
 constructor(){
 //...
 }
  static ring(){}
  send(){}
}

// => 工厂模式

class Child extends Course{
 constructor(){
  super('aa',es6) //相当于Course.call(this,'aa','es6')
  }
  run(){}
 }