Stage 1 Draft / September 9, 2025

Await Dictionary

1 Promise.allKeyed ( promises )

This method performs the following steps when called:

  1. Let C be the this value.
  2. Let promiseCapability be ? NewPromiseCapability(C).
  3. Let promiseResolve be Completion(GetPromiseResolve(C)).
  4. IfAbruptRejectPromise(promiseResolve, promiseCapability).
  5. If promises is not an Object, then
    1. Let error be a newly created TypeError object.
    2. Perform ? Call(promiseCapability.[[Reject]], undefined, « error »).
    3. Return promiseCapability.[[Promise]].
  6. Let result be Completion(PerformPromiseAllKeyed(promises, C, promiseCapability, promiseResolve)).
  7. IfAbruptRejectPromise(result, promiseCapability).
  8. Return promiseCapability.[[Promise]].
 Note

This function requires its this value to be a constructor function that supports the parameter conventions of the Promise constructor.

1.1 PerformPromiseAllKeyed ( promises, constructor, resultCapability, promiseResolve )

The abstract operation PerformPromiseAllKeyed takes arguments promises (an Object), constructor (a constructor), resultCapability (a PromiseCapability Record), and promiseResolve (a function object) and returns either a normal completion containing an ECMAScript language value or a throw completion. It performs the following steps when called:

  1. Let allKeys be ? promises.[[OwnPropertyKeys]]().
  2. Let keys be a new empty List.
  3. Let values be a new empty List.
  4. Let remainingElementsCount be the Record { [[Value]]: 1 }.
  5. Let index be 0.
  6. For each element key of allKeys, do
    1. Let desc be ? promises.[[GetOwnProperty]](key).
    2. If desc is not undefined and desc.[[Enumerable]] is true, then
      1. Let value be ? Get(promises, key).
      2. Append key to keys.
      3. Append undefined to values.
      4. Let nextPromise be ? Call(promiseResolve, constructor, « value »).
      5. Let steps be the algorithm steps defined in Promise.allKeyed Resolve Element Functions.
      6. Let length be the number of non-optional parameters of the function definition in Promise.allKeyed Resolve Element Functions.
      7. Let onFulfilled be CreateBuiltinFunction(steps, length, "", « [[AlreadyCalled]], [[Index]], [[Keys]], [[Values]], [[Capability]], [[RemainingElements]] »).
      8. Set onFulfilled.[[AlreadyCalled]] to false.
      9. Set onFulfilled.[[Index]] to index.
      10. Set onFulfilled.[[Keys]] to keys.
      11. Set onFulfilled.[[Values]] to values.
      12. Set onFulfilled.[[Capability]] to resultCapability.
      13. Set onFulfilled.[[RemainingElements]] to remainingElementsCount.
      14. Set remainingElementsCount.[[Value]] to remainingElementsCount.[[Value]] + 1.
      15. Perform ? Invoke(nextPromise, "then", « onFulfilled, resultCapability.[[Reject]] »).
      16. Set index to index + 1.
  7. Set remainingElementsCount.[[Value]] to remainingElementsCount.[[Value]] - 1.
  8. If remainingElementsCount.[[Value]] = 0, then
    1. Let result be OrdinaryObjectCreate(null).
    2. Perform ? Call(resultCapability.[[Resolve]], undefined, « result »).
  9. Return resultCapability.[[Promise]].

1.2 Promise.allKeyed Resolve Element Functions

A Promise.all resolve element function is an anonymous built-in function

When a Promise.allKeyed resolve element function is called with argument x, the following steps are taken:

  1. Let F be the active function object.
  2. If F.[[AlreadyCalled]] is true, return undefined.
  3. Set F.[[AlreadyCalled]] to true.
  4. Let index be F.[[Index]].
  5. Let keys be F.[[Keys]].
  6. Let values be F.[[Values]].
  7. Let promiseCapability be F.[[Capability]].
  8. Let remainingElementsCount be F.[[RemainingElements]].
  9. Set values[index] to x.
  10. Set remainingElementsCount.[[Value]] to remainingElementsCount.[[Value]] - 1.
  11. If remainingElementsCount.[[Value]] = 0, then
    1. Let result be OrdinaryObjectCreate(null).
    2. For each integer i such that 0 ≤ i < the number of elements in keys, in ascending order, do
      1. Perform ! CreateDataPropertyOrThrow(result, keys[i], values[i]).
    3. Return ? Call(promiseCapability.[[Resolve]], undefined, « result »).
  12. Return undefined.

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