利用promise实现间隔1s打印1，2，3

Posted 2020-11-28 samsara-yx

利用promise结合数组的rduce方法

        let arr = [1, 2, 3];
        arr.reduce((pre, cur) => {
            return pre.then(() => {
                return new Promise(r => {
                    setTimeout(() => {
                        r(console.log(cur))
                    }, 1000);
                })
            })
        }, Promise.resolve())