promise.allsettled polyfill provides a reliable implementation of the Promise.allSettled method introduced in ES2020. This function takes an iterable of promises and returns a single promise that resolves after all input promises have either resolved or rejected. The resolved value is an array of objects, each describing the outcome of the corresponding input promise, indicating whether it fulfilled and its value or rejected and its reason. It ensures all promises are processed, regardless of individual successes or failures.