const myPromise = new Promise((resolve, reject) => {
  setTimeout(() => {
    resolve("foo");
  }, 2000);
    // reject("12222")
});

myPromise.then((value) => {
  console.log(value); // 2000毫秒后打印  "foo"
}).catch( error => {
  console.log(error)
})

// myPromise.catch()   也可以单独写catch  链式操作

可打印 Promise 对象查看

参考

• Promise - JavaScript | MDN (opens new window)