实现sleep函数

Promise

    function sleep(time = 1) {
        return new Promise((resolve, reject) => {
            setTimeout(() => {
                resolve(true)
            }, time);
        })
    }

while循环

    function sleep(time = 1) {
        let start = +Date.now()
        while(true) {
            if (+Date.now() - start >= time) break
        }
    }

for循环

    function sleep(time = 1) {
        for(let t = Date.now(); Date.now() - t <= time;) {}
    }