面试高频手撕代码题

Promise 系列

实现 Promise.race()

const promiseRace = promises => {
  return new Promise((resolve, reject) => {
    promises.forEach((promise, index) => {
      Promise.resolve(promise).then(
        res => {
          resolve(res);
        },
        err => {
          reject(err);
        }
      );
    });
  });
};

// test
const p1 = new Promise(resolve => {
  setTimeout(resolve, 105, 'p1 done');
});
const p2 = new Promise(resolve => {
  setTimeout(resolve, 100, 'p2 done');
});
promiseRace([p1, p2]).then(data => {
  console.log(data); // p2 done，可以看到 p2 先被执行，执行完就结束了
});