对象属性的遍历

爱学习的前端歌谣

发布于 2023-10-24 07:06:26

79800

代码可运行

文章被收录于专栏：前端小歌谣前端小歌谣

运行总次数：0

代码可运行

前言

我是歌谣最好的种树是十年前其次是现在今天继续给大家带来的是对象属性的讲解

环境配置

npm init -y
yarn add vite -D

修改page.json配置端口

{
  "name": "demo1",
  "version": "1.0.0",
  "description": "",
  "main": "index.js",
  "scripts": {
    "dev": "vite --port 3002"
  },
  "keywords": [],
  "author": "",
  "license": "ISC",
  "devDependencies": {
    "vite": "^4.4.9"
  }
}

案例1

var arr=[1,2,3,4,5]
for(var i=0;i<arr.length;i++){
    console.log(arr[i])
}

运行结果

案例2

 var arr=[1,2,3,4,5]
// for(var i=0;i<arr.length;i++){
//     console.log(arr[i])
// }
var car={
    brand:'Benz',
    color:'red',
    displament:'3.0',
    name:'geyao'
}
for(var key in car){
    console.log(key+'+'+car[key])
}
for(var key in arr){
    console.log(arr[key])
}

运行结果

案例3

var obj={
    name:"geyao",
    age:22
}
function Car(){
    this.brand="Benz",
    this.color="red",
    this.size=18
}
Car.prototype={
    age:18,
    width:2.5
}
Object.prototype.sex="女"
var car=new Car()
for(var key in car){
    console.log(key+'+'+car[key])
}

运行结果

案例4

var geyao={
    name:"geyao",
    age:18
}
console.log('age' in geyao) //true


function Car(){
    this.brand='TAGE',
    this.color='red'
}
Car.prototype={
    displacement:'3.0'
}
var car=new Car();
console.log('displacement' in car)

运行结果

案例5

function Car(){


}
var car=new Car()


function Person(){


}
console.log(car instanceof Car)
console.log(car instanceof Object)
console.log([] instanceof Array)
console.log([] instanceof Object)
console.log({} instanceof Object)

运行结果

案例6

const a=[]
console.log(a.constructor)
console.log( a instanceof Array)
var str=Object.prototype.toString.call(a)
console.log(str)
var arr=new Array(1,2,3)
console.log(arr)