function sleep(time) {
            return new Promise((resolve, reject) => {
                setTimeout(() => {
                    resolve()
                }, time)
            })
        }
        (async () => {
            for (let i = 0; i < 5; i++) {
                await sleep(1000)
                console.log(i);
            }
        })()

最后输出0,1,2,3,4，每个输出间隔一秒