promise.all.js

const getRandom = () => +(Math.random() * 1000).toFixed(0);

const asyncTask = taskID => new Promise(resolve => {
  let timeout = getRandom();
  console.log(`taskID=${taskID} start.`);
  setTimeout(function () {
    console.log(`taskID=${taskID} finished in time=${timeout}.`);
    resolve(taskID)
  }, timeout);
});
Promise.all([asyncTask(1), asyncTask(2), asyncTask(3)])
  .then(resultList => {
    console.log('results:', resultList);
  });

const asyncTaskErr = taskID => new Promise((resolve, reject) => {
  let timeout = getRandom();
  console.log(`taskErrID=${taskID} start.`);
  setTimeout(function () {
    console.log(`taskErrID=${taskID} finished in time=${timeout}.`);
    reject(taskID)
  }, timeout);
});
Promise.all([asyncTaskErr(1), asyncTaskErr(2), asyncTaskErr(3)])
  .then(resultList => {
    console.log('task err results:', resultList);
  }).catch(e => {
    console.error('task err err', e);
  });

const asyncTaskErrWithCatch = taskID => new Promise((resolve, reject) => {
  let timeout = getRandom();
  console.log(`taskErrCatchID=${taskID} start.`);
  setTimeout(function () {
    console.log(`taskErrCatchID=${taskID} finished in time=${timeout}.`);
    reject(taskID)
  }, timeout);
}).catch(e => {
  console.log('taskErrCatchAtCatch', e);
  return new Error('e');
});
Promise.all([asyncTaskErrWithCatch(1), asyncTaskErrWithCatch(2), asyncTaskErrWithCatch(3)])
  .then(resultList => {
    console.log('task err catch results:', resultList);
  }).catch(e => {
    console.error('task err catch err', e);
  });