关于javascript:手写count-函数和sleep-睡眠函数

count 函数

每次调用一个函数主动加 1

count() 1count() 2count() 3

var count = (function () {  var a = 0  return function () {    console.log(++a)  }})()count() // 1count() // 2count() // 3

sleep 睡眠函数

比方 sleep(1000)代表期待 1000ms

办法一：ES5 形式实现

function sleep(callback, time) {  if (typeof callback == 'function') {    setTimeout(callback, time)  }}function output() {  console.log(111)}sleep(output, 2000)

办法二：应用 promise 形式

const sleep = (time) => {  return new Promise((resolve) => {    setTimeout(resolve, time)  })}sleep(2000).then(() => {  console.log(111)})

办法三：利用 async

function sleep(ms) {  return new Promise((resolve) => {    setTimeout(resolve, ms)  })}async function init() {  var temp = await sleep(2000)  console.log(111) //2s后执行}init()