Promise

gistfile1.txt

let success = (value) => {
  console.log('success', value)
}

let fail = (value) => {
  console.log('fail', value)
}

let action = (name) => {
  return new Promise((resolve, reject) => {
    let now = Date.now();
    if (now % 2 === 0) {
      resolve(`${name} now is even: ${now}`);
    } else {
      reject(`${name} now is odd: ${now}`);
    }
  });
};

window.addEventListener('click', () => {
  let p = action("p").then(success, fail);
});