实现一个 sleep 函数

（一）Promise 实现

const sleep = (timeout) => {
    return new Promise(resolve => setTimeout(resolve, timeout));
};
sleep(1000).then(() => {
    console.log("best Cindy");
});

（二）Generator

function* sleepGenerator(time) {
    yield new Promise(function (resolve, reject) {
        setTimeout(resolve, time);
    });
};
sleepGenerator(1000).next().value.then(() => { console.log("best Cindy") });

（三）async await

function sleep(time) {
    return new Promise(resolve => setTimeout(resolve,time))
};
async function output() {
    let out = await sleep(1000);
    console.log("best Cindy");
    return out;
};
output();

（四）ES5

function sleep(callback,time) {
    if(typeof callback === 'function')
        setTimeout(callback,time)
};
function output(){
    console.log("best Cindy");
};
sleep(output,1000);