SOURCE

let arr=[1,2,3]
let type=Object.prototype.toString.call(arr)
let type2=type.split(" ")[1].split("")
console.log(type)
console.log(type2)
type2.pop()
console.log(type2.join(""))

Function.prototype.myCall=function(obj){
    if(typeof this !== 'function'){
        throw Error('wrong type')
    }
    var obj=obj||window
    let args=[...arguments].slice(1)
    console.log(...args)
    obj.p=this
    let result=obj.p(...args)
    delete obj.p
    return result
}

function add(a,b,c){
    console.log(a+b+c)
    console.log(this.a)
}
add.myCall(null,1,2,3)

let newfun=add.bind({a:2},2)
console.log(newfun)
let newfun2=new newfun(2,3,4)
console.log(newfun2)

Function.prototype.myBind=function(obj){
    if(typeof this !== 'function'){
        throw Error("type error")
    }
    let args=[...arguments].slice(1)
    let _this=this
    return function fn(){
        return _this.apply(this instanceof fn?this:obj,args.concat(...arguments))
    }
}
let testfun=add.myBind({a:1},3)
console.log(testfun)
let testfun2=new testfun(4,5,6)
console.log(testfun2)

let date=new Date('2021-09-25')
console.log(typeof date)

function deepClone(obj){
    if(!obj||typeof obj !=="object"){
        return 
    }
    if(obj instanceof Date){
        return new Date(obj)
    }
    if(obj instanceof RegExp){
        console.log(obj+'1')
        return new RegExp(obj)
    }
    let newobj=Array.isArray()?[]:{}
    for(let key in obj){
        if(obj.hasOwnProperty(key)){
            newobj[key]=typeof obj[key]!=="object"?obj[key]:deepClone(obj[key])
        }
    }
    return newobj
}
let exp=/cat/g;
let reg=new RegExp(exp)
console.log(reg)
var obj={
    name:'lii',
    add:add,
    hobby:[1,'si',{a:1}],
    date:date,
    exp:reg
}
let newoo=deepClone(obj)
let newoo2=deepClone(obj)
newoo.date=new Date('2020-09-25')
console.log(newoo)
console.log(newoo2)
console.log(obj)
console.log(obj.exp)