.race()

Returns the first Promise in an iterableObject that is either resolved or rejected.

Syntax

Promise.race(iterableObject);

Example #1

If the iterableObject is empty, then the returned Promise will be in “pending” forever and never resolve.

const emptyPromises = [];

Promise.race(emptyPromises).then((result) => {
  console.log(result); // Nothing logged to the console
});

Example #2

In the spirit of a race, ssing setTimeout() within two runners named runnerA and runnerB:

const runnerA = new Promise((resolve, reject) => {
  setTimeout(reject, 100, 'The winner is runnerA!');
});

const runnerB = new Promise((resolve, reject) => {
  setTimeout(resolve, 300, 'The winner is runnerB!');
});

const promises = [runnerA, runnerB];

Promise.race(promises)
  .then((result) => {
    console.log(result);
  })
  .catch((err) => {
    console.log(err);
  })
  .finally(() => {
    console.log('Operations for Promise.race() have finished.');
  });