https://developer.mozilla.org/zh-CN/docs/Web/JavaScript/Reference/Global_Objects/Promise#%E7%A4%BA%E4%BE%8B
主要问题，解决异步回调的烦人写法

Race

两个异步任务同时执行，听从先有反馈的

const promise1 = new Promise((resolve, reject) => {
  setTimeout(resolve, 500, 'one');
});
const promise2 = new Promise((resolve, reject) => {
  setTimeout(resolve, 100, 'two');
});
Promise.race([promise1, promise2]).then((value) => {
  console.log(value);
  // Both resolve, but promise2 is faster
});
// expected output: "two"