Wait for all promises to completed, even rejected promises.

waitAllPromisesCompleted.js

const first = new Promise((resolve, reject) => {
  setTimeout(() => resolve("first"), 1000);
});

const second = new Promise((resolve, reject) => {
  setTimeout(() => reject("second error"), 2000);
});

const third = new Promise((resolve, reject) => {
  setTimeout(() => resolve("third"), 3000);
});

const fourth = new Promise((resolve, reject) => {
  setTimeout(() => reject("fourth error"), 4000);
});

const fifth = new Promise((resolve, reject) => {
  setTimeout(() => resolve("fifth"), 5000);
});

/* By default, when any of the promises is rejected,
 * Promise.all() will return error immediately without waiting for other unfinished promises.
 * 
 * With following approach, we can wait for all promises to completed, even rejected promises.
 * We achieve this by turning the rejected promises into the resolved ones with map() before passing promises to Promise.all().
 * Therefore, all promises will be resolved and we can wait for them to completed.
 *
 * Output:
 *    Catched error: second error
 *    Catched error: fourth error
 *    Results:
 *    [ 'first', 'second error', 'third', 'fourth error', 'fifth' ]
 */
Promise.all([first, second, third, fourth, fifth].map(p => {
  return p.catch(e => {
    console.log("Catched error: " + e);
    return e;
  });
}))
.then(results => {
  console.log("Results:");
  console.log(results);
})
.catch(e => {
  console.log("Error: " + e); // Never executed, just keep it as good practice.
});

https://stackoverflow.com/questions/31424561/wait-until-all-es6-promises-complete-even-rejected-promises