Does promise all always return in order?
Promise.all() will reject immediately upon any of the input promises rejecting. Consequently, it will always return the final result of every promise and function from the input iterable.
What is promise reduce?
reduce. If the reducer function returns a promise, then the result of the promise is awaited, before continuing with next iteration. If any promise in the array is rejected or a promise returned by the reducer function is rejected, the result is rejected as well.
Does Promise reject to catch?
catch() The catch() method returns a Promise and deals with rejected cases only. It behaves the same as calling Promise.
Is the Order of resolved values preserved in promise.all?
As the previous answers have already stated, Promise.all aggregates all resolved values with an array corresponding to the input order of the original Promises (see Aggregating Promises ). However, I would like to point out, that the order is only preserved on the client side!
Is the Order of values in promise.all the same?
Yes, the values in results are in the same order as the promises. One might cite the ES6 spec on Promise.all, though it’s a bit convoluted due to the used iterator api and generic promise constructor.
Why are the promises in order in JavaScript?
The three Promises execute at different speeds (C being the fastest and B being the slowest). That’s why the console.log statements of the Promises show up in this order: If the Promises are AJAX calls, then a remote backend will receive these values in this order.
How is the Order of resolved values determined?
Resolving is implemented via Promise.all () Resolve where each resolved promise has an internal [ [Index]] slot, which marks the index of the promise in the original input. All this means that the output is strictly ordered as the input as long as the input is strictly ordered (for example, an array).