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