When you have a promise, sometimes you want to ensure that some code always runs, regardless of the outcome of the promise. For example, you may want to hide a loading spinner or close a file connection whether the operation was successful or not. Before finally(), developers had to duplicate code in both the .then() and .catch() blocks. finally() eliminates that redundancy.

fetchData()
  .then((data) => {
    console.log('Data fetched successfully', data);
  })
  .catch((error) => {
    console.error('Error fetching data', error);
  })
  .finally(() => {
    hideLoadingSpinner(); // Runs no matter the result
  });