let

const

destructuring

字串的擴充套件

數值的擴充套件

物件的擴充套件

Promise

const promise = new Promise ((resolve, rereject) => {
  if (/* 非同步操作成功 */){
    return resolve(value);
  } else {
    return reject(error);
  }
})

promise.then((value) => {
  // success
}, (error) => {
  // failure
});