js实现sleep函数

方法一

function sleep1(ms, cb){
    setTimeout(cb, ms);
}

sleep1(3000, () => {
    console.log(222);
});

方法二

function sleep2(ms){
    return new Promise((resolve, reject) => {
        setTimeout(resolve, ms);
    });
}

sleep2(3000).then(() => {
    console.log(222);
});