JS优雅的使用function实现一个class

class MyClass{
    constructor(name){
        this.name = name
    }
    fun(){
        console.log('myName:'+this.name)
    }
}

function MyClass1(name){
    this.name = name
}
MyClass1.prototype.fun = function(){
    console.log('myName:'+this.name)
}
let m1 = new MyClass1('aaa')
m1.fun() //myName:aaa

class MyClass{
    constructor(name){
        this.name = name
    }
    fun(){
        console.log('myName:'+this.name)
    }
}
// MyClass('aaa') //TypeError: Class constructor MyClass cannot be invoked without 'new'

function MyClass1(name){
    console.log(this)
    this.name = name
}
let m1 = new MyClass1('aaa') //MyClass1 {}
MyClass1('aaa') //window

function MyClass1(name){
    console.log(this)
    if(!(this instanceof MyClass)){ //如果this不是指向MyClass
        throw new TypeError('TypeError: Class constructor MyClass cannot be invoked without 'new'')
    }
    this.name = name
}

let m = new MyClass('aaa')
for(let i in m){
    console.log(i) //name
}
let m1 = new MyClass1('aaa')
for(let i in m1){
    console.log(i) //name fn
}

'use strict'
function MyClass1(name){
    this.name = name
}
Object.defineProperty(MyClass1.prototype,'fn',{
    value:function(){
        console.log('myName:'+this.name)
    },
    enumerable:false
})

let m = new MyClass('aaa')
new m.fun() //TypeError: m.fun is not a constructor

Object.defineProperty(MyClass1.prototype,'fn',{
    value:function(){
        //不可通过new调用 
        console.log(this) //正常调用下的this是指向实例 MyClass1 { name: 'aaa' }
        if(!(this instanceof MyClass1){//那么相反 不是正常调用的就是错误的调用
            //error
        }
        console.log('myName:'+this.name)
    },
    enumerable:false
})

'use strict'
function MyClass1(name){
    this.name = name
}
Object.defineProperty(MyClass1.prototype,'fn',{
    value:function(){
        console.log(this)
        if(!(this instanceof MyClass1)){
            //error
            throw TypeError('error')
        }
        console.log('myName:'+this.name)
    },
    enumerable:false
})
let m1 = new MyClass1('aaa')
m1.fn()
// new m1.fn() //error
for(let i in m1){
    console.log(i) //name
}