.catch()

Returns a new Promise related to a previously rejected Promise in the chain. This is ideal for formatting error messages for potential Promise rejections.

myPromiseObject.catch(rejectedPromiseCallback);

The rejectedPromiseCallback function will have access to all reject() data inside of myProjectObject.

Inside the brokenPromise is a single reject() call with error information. It is then handled inside .catch().

const brokenPromise = new Promise((resolve, reject) => {
  reject({
    errorType: 'Unknown error',
    message: 'Something went wrong.',
  });
});

brokenPromise.catch((err) => {
  console.log(`${err.errorType}: ${err.message}`); // Unknown error: Something went wrong.
});