实现sleep函数

1.使用async,await

function sleep(time){
    return new Promise((resolve,reject)=>{
      setTimeout(resolve,time)
    })
  }
  async function init(){
    console.log('do something')
    await sleep(3000)
    console.log('睡完之后 do something')

  }

2.

function sleep(callback,time){
    setTimeout(callback,time)
  }
  sleep(()=>{
    console.log('睡一段时间后,我就执行了')
  },5000)