Why Promise.allSettled Beats Promise.all for Robust Async JavaScript

Handling asynchronous operations has become core in JavaScript coding. As applications grow, we often need to run multiple async tasks concurrently and handle their results. Traditionally, Promise.all() has been the go‑to method for concurrent promises, but it has a fatal flaw: if any promise is rejected, the whole operation fails.

Limitations of Promise.all

Recall how Promise.all() works and its limitations:

The main problems are:

Any rejected promise causes the entire operation to fail.

You cannot know which operations succeeded and which failed.

You cannot retrieve the results of successful operations.

In real applications we often want to continue processing successful results even when some operations fail—for example, displaying other dashboard components when one component’s data request fails.

Promise.allSettled to the rescue

Promise.allSettled()

solves all the above issues. It waits for every promise to settle (fulfilled or rejected) and returns an array containing each promise’s result:

Structure of Promise.allSettled’s return value

The return value of Promise.allSettled() is an array where each element corresponds to a promise and has the following shape:

For a fulfilled promise: { status: 'fulfilled', value: <result> } For a rejected promise: { status: 'rejected', reason: <error> } This uniform structure makes result handling straightforward. In scenarios that require concurrent execution of independent async operations while still needing the complete set of outcomes regardless of individual success, Promise.allSettled() is the ideal choice, allowing developers to build more resilient applications that gracefully handle inevitable errors and exceptions.