前端歌谣-第贰拾陆课-闭包

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闭包的讲解

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

function test1(){
    function test2(){
        var b=2;
        console.log(a)
    }
    var a=1;
    return test2()
}
var c=3
var test3=test1();

分析

案例2

function test(){
    var n=100
    function add(){
        n++
        console.log(n)
    }
    function reduce(){
        n--
        console.log(n)
    }
    return [add,reduce]
}
var arr=test()
arr[0]()
arr[1]()

运行结果

案例2

function breadMsg(num) {
    var breadNum = arguments[0] || 10
    function supply() {
        breadNum += 10
        console.log(breadNum)
    }
    function sale() {
        breadNum -= 10
        console.log(breadNum)
    }
    return [supply, sale]
}
var breadMsg = breadMsg(50)
breadMsg[0](10)

运行结果

案列3

function sunSched(){
    var sunSched=''
    var opration={
        setSched:function(thing){
            sunSched=thing
        },
        showSched:function(){
            console.log("MY schedule on sunday is "+sunSched)
        }
    }
    return opration
}
var sunSch=sunSched()
sunSch.setSched("studying")
sunSch.showSched()

运行结果