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() 1
count() 2
count() 3

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