Promise

promise.js

const p = new Promise((resolve, reject) => {
  const a = 1 + 1;
  if (a === 2) {
    resolve('Success');
  } else {
    reject('Faild');
  }
});

p.then((message) => {
  console.log(message);
}).catch((error) => {
  console.log(error);
});