Array中使用异步函数遍历元素

        const arr = [1, 2, 3];

        async function fn() {
            await arr.reduce(async (accumulator, currentValue) => {
                await accumulator;
                await sleep(2000);
                console.log(currentValue);
            }, undefined);
        };
        fn();

        async function sleep(arg) {
            return new Promise(resolve => {
                setTimeout(function () {
                    resolve(arg);
                }, arg);
            })
        }