Adding upstream version 124.0.1.upstream/124.0.1

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

1 files changed, 1509 insertions, 0 deletions

diff --git a/js/src/vm/AsyncIteration.cpp b/js/src/vm/AsyncIteration.cpp
new file mode 100644
index 0000000000..8f8902a64a
--- /dev/null
+++ b/js/src/vm/AsyncIteration.cpp
@@ -0,0 +1,1509 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*-
+ * vim: set ts=8 sts=2 et sw=2 tw=80:
+ * This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#include "vm/AsyncIteration.h"
+
+#include "builtin/Promise.h"  // js::PromiseHandler, js::CreatePromiseObjectForAsyncGenerator, js::AsyncFromSyncIteratorMethod, js::ResolvePromiseInternal, js::RejectPromiseInternal, js::InternalAsyncGeneratorAwait
+#include "js/friend/ErrorMessages.h"  // js::GetErrorMessage, JSMSG_*
+#include "js/PropertySpec.h"
+#include "vm/CompletionKind.h"
+#include "vm/FunctionFlags.h"  // js::FunctionFlags
+#include "vm/GeneratorObject.h"
+#include "vm/GlobalObject.h"
+#include "vm/Interpreter.h"
+#include "vm/PlainObject.h"    // js::PlainObject
+#include "vm/PromiseObject.h"  // js::PromiseObject
+#include "vm/Realm.h"
+#include "vm/SelfHosting.h"
+
+#include "vm/JSObject-inl.h"
+#include "vm/List-inl.h"
+
+using namespace js;
+
+// ---------------
+// Async generator
+// ---------------
+
+const JSClass AsyncGeneratorObject::class_ = {
+    "AsyncGenerator",
+    JSCLASS_HAS_RESERVED_SLOTS(AsyncGeneratorObject::Slots),
+    &classOps_,
+};
+
+const JSClassOps AsyncGeneratorObject::classOps_ = {
+    nullptr,                                   // addProperty
+    nullptr,                                   // delProperty
+    nullptr,                                   // enumerate
+    nullptr,                                   // newEnumerate
+    nullptr,                                   // resolve
+    nullptr,                                   // mayResolve
+    nullptr,                                   // finalize
+    nullptr,                                   // call
+    nullptr,                                   // construct
+    CallTraceMethod<AbstractGeneratorObject>,  // trace
+};
+
+// ES2022 draft rev 193211a3d889a61e74ef7da1475dfa356e029f29
+//
+// OrdinaryCreateFromConstructor ( constructor, intrinsicDefaultProto
+//                                 [ , internalSlotsList ] )
+// https://tc39.es/ecma262/#sec-ordinarycreatefromconstructor
+//
+// specialized for AsyncGeneratorObjects.
+static AsyncGeneratorObject* OrdinaryCreateFromConstructorAsynGen(
+    JSContext* cx, HandleFunction constructor) {
+  // Step 1: Assert...
+  // (implicit)
+
+  // Step 2. Let proto be
+  //         ? GetPrototypeFromConstructor(constructor, intrinsicDefaultProto).
+  RootedValue protoVal(cx);
+  if (!GetProperty(cx, constructor, constructor, cx->names().prototype,
+                   &protoVal)) {
+    return nullptr;
+  }
+
+  RootedObject proto(cx, protoVal.isObject() ? &protoVal.toObject() : nullptr);
+  if (!proto) {
+    proto = GlobalObject::getOrCreateAsyncGeneratorPrototype(cx, cx->global());
+    if (!proto) {
+      return nullptr;
+    }
+  }
+
+  // Step 3. Return ! OrdinaryObjectCreate(proto, internalSlotsList).
+  return NewObjectWithGivenProto<AsyncGeneratorObject>(cx, proto);
+}
+
+// ES2022 draft rev 193211a3d889a61e74ef7da1475dfa356e029f29
+//
+// AsyncGeneratorStart ( generator, generatorBody )
+// https://tc39.es/ecma262/#sec-asyncgeneratorstart
+//
+// Steps 6-7.
+/* static */
+AsyncGeneratorObject* AsyncGeneratorObject::create(JSContext* cx,
+                                                   HandleFunction asyncGen) {
+  MOZ_ASSERT(asyncGen->isAsync() && asyncGen->isGenerator());
+
+  AsyncGeneratorObject* generator =
+      OrdinaryCreateFromConstructorAsynGen(cx, asyncGen);
+  if (!generator) {
+    return nullptr;
+  }
+
+  // Step 6. Set generator.[[AsyncGeneratorState]] to suspendedStart.
+  generator->setSuspendedStart();
+
+  // Step 7. Set generator.[[AsyncGeneratorQueue]] to a new empty List.
+  generator->clearSingleQueueRequest();
+
+  generator->clearCachedRequest();
+
+  return generator;
+}
+
+/* static */
+AsyncGeneratorRequest* AsyncGeneratorObject::createRequest(
+    JSContext* cx, Handle<AsyncGeneratorObject*> generator,
+    CompletionKind completionKind, HandleValue completionValue,
+    Handle<PromiseObject*> promise) {
+  if (!generator->hasCachedRequest()) {
+    return AsyncGeneratorRequest::create(cx, completionKind, completionValue,
+                                         promise);
+  }
+
+  AsyncGeneratorRequest* request = generator->takeCachedRequest();
+  request->init(completionKind, completionValue, promise);
+  return request;
+}
+
+/* static */ [[nodiscard]] bool AsyncGeneratorObject::enqueueRequest(
+    JSContext* cx, Handle<AsyncGeneratorObject*> generator,
+    Handle<AsyncGeneratorRequest*> request) {
+  if (generator->isSingleQueue()) {
+    if (generator->isSingleQueueEmpty()) {
+      generator->setSingleQueueRequest(request);
+      return true;
+    }
+
+    Rooted<ListObject*> queue(cx, ListObject::create(cx));
+    if (!queue) {
+      return false;
+    }
+
+    RootedValue requestVal(cx, ObjectValue(*generator->singleQueueRequest()));
+    if (!queue->append(cx, requestVal)) {
+      return false;
+    }
+    requestVal = ObjectValue(*request);
+    if (!queue->append(cx, requestVal)) {
+      return false;
+    }
+
+    generator->setQueue(queue);
+    return true;
+  }
+
+  Rooted<ListObject*> queue(cx, generator->queue());
+  RootedValue requestVal(cx, ObjectValue(*request));
+  return queue->append(cx, requestVal);
+}
+
+/* static */
+AsyncGeneratorRequest* AsyncGeneratorObject::dequeueRequest(
+    JSContext* cx, Handle<AsyncGeneratorObject*> generator) {
+  if (generator->isSingleQueue()) {
+    AsyncGeneratorRequest* request = generator->singleQueueRequest();
+    generator->clearSingleQueueRequest();
+    return request;
+  }
+
+  Rooted<ListObject*> queue(cx, generator->queue());
+  return &queue->popFirstAs<AsyncGeneratorRequest>(cx);
+}
+
+/* static */
+AsyncGeneratorRequest* AsyncGeneratorObject::peekRequest(
+    Handle<AsyncGeneratorObject*> generator) {
+  if (generator->isSingleQueue()) {
+    return generator->singleQueueRequest();
+  }
+
+  return &generator->queue()->getAs<AsyncGeneratorRequest>(0);
+}
+
+const JSClass AsyncGeneratorRequest::class_ = {
+    "AsyncGeneratorRequest",
+    JSCLASS_HAS_RESERVED_SLOTS(AsyncGeneratorRequest::Slots)};
+
+// ES2022 draft rev 193211a3d889a61e74ef7da1475dfa356e029f29
+//
+// AsyncGeneratorRequest Records
+// https://tc39.es/ecma262/#sec-asyncgeneratorrequest-records
+/* static */
+AsyncGeneratorRequest* AsyncGeneratorRequest::create(
+    JSContext* cx, CompletionKind completionKind, HandleValue completionValue,
+    Handle<PromiseObject*> promise) {
+  AsyncGeneratorRequest* request =
+      NewObjectWithGivenProto<AsyncGeneratorRequest>(cx, nullptr);
+  if (!request) {
+    return nullptr;
+  }
+
+  request->init(completionKind, completionValue, promise);
+  return request;
+}
+
+[[nodiscard]] static bool AsyncGeneratorResume(
+    JSContext* cx, Handle<AsyncGeneratorObject*> generator,
+    CompletionKind completionKind, HandleValue argument);
+
+[[nodiscard]] static bool AsyncGeneratorDrainQueue(
+    JSContext* cx, Handle<AsyncGeneratorObject*> generator);
+
+[[nodiscard]] static bool AsyncGeneratorCompleteStepNormal(
+    JSContext* cx, Handle<AsyncGeneratorObject*> generator, HandleValue value,
+    bool done);
+
+[[nodiscard]] static bool AsyncGeneratorCompleteStepThrow(
+    JSContext* cx, Handle<AsyncGeneratorObject*> generator,
+    HandleValue exception);
+
+// ES2022 draft rev 193211a3d889a61e74ef7da1475dfa356e029f29
+//
+// AsyncGeneratorStart ( generator, generatorBody )
+// https://tc39.es/ecma262/#sec-asyncgeneratorstart
+//
+// Steps 4.e-j. "return" case.
+[[nodiscard]] static bool AsyncGeneratorReturned(
+    JSContext* cx, Handle<AsyncGeneratorObject*> generator, HandleValue value) {
+  // Step 4.e. Set generator.[[AsyncGeneratorState]] to completed.
+  generator->setCompleted();
+
+  // Step 4.g. If result.[[Type]] is return, set result to
+  //           NormalCompletion(result.[[Value]]).
+  // (implicit)
+
+  // Step 4.h. Perform ! AsyncGeneratorCompleteStep(generator, result, true).
+  if (!AsyncGeneratorCompleteStepNormal(cx, generator, value, true)) {
+    return false;
+  }
+
+  // Step 4.i. Perform ! AsyncGeneratorDrainQueue(generator).
+  // Step 4.j. Return undefined.
+  return AsyncGeneratorDrainQueue(cx, generator);
+}
+
+// ES2022 draft rev 193211a3d889a61e74ef7da1475dfa356e029f29
+//
+// AsyncGeneratorStart ( generator, generatorBody )
+// https://tc39.es/ecma262/#sec-asyncgeneratorstart
+//
+// Steps 4.e-j. "throw" case.
+[[nodiscard]] static bool AsyncGeneratorThrown(
+    JSContext* cx, Handle<AsyncGeneratorObject*> generator) {
+  // Step 4.e. Set generator.[[AsyncGeneratorState]] to completed.
+  generator->setCompleted();
+
+  // Not much we can do about uncatchable exceptions, so just bail.
+  if (!cx->isExceptionPending()) {
+    return false;
+  }
+
+  // Step 4.h. Perform ! AsyncGeneratorCompleteStep(generator, result, true).
+  RootedValue value(cx);
+  if (!GetAndClearException(cx, &value)) {
+    return false;
+  }
+  if (!AsyncGeneratorCompleteStepThrow(cx, generator, value)) {
+    return false;
+  }
+
+  // Step 4.i. Perform ! AsyncGeneratorDrainQueue(generator).
+  // Step 4.j. Return undefined.
+  return AsyncGeneratorDrainQueue(cx, generator);
+}
+
+// ES2022 draft rev 193211a3d889a61e74ef7da1475dfa356e029f29
+//
+// AsyncGeneratorUnwrapYieldResumption ( resumptionValue )
+// https://tc39.es/ecma262/#sec-asyncgeneratorunwrapyieldresumption
+//
+// Steps 4-5.
+[[nodiscard]] static bool AsyncGeneratorYieldReturnAwaitedFulfilled(
+    JSContext* cx, Handle<AsyncGeneratorObject*> generator, HandleValue value) {
+  MOZ_ASSERT(generator->isAwaitingYieldReturn(),
+             "YieldReturn-Await fulfilled when not in "
+             "'AwaitingYieldReturn' state");
+
+  // Step 4. Assert: awaited.[[Type]] is normal.
+  // Step 5. Return Completion { [[Type]]: return, [[Value]]:
+  //         awaited.[[Value]], [[Target]]: empty }.
+  return AsyncGeneratorResume(cx, generator, CompletionKind::Return, value);
+}
+
+// ES2022 draft rev 193211a3d889a61e74ef7da1475dfa356e029f29
+//
+// AsyncGeneratorUnwrapYieldResumption ( resumptionValue )
+// https://tc39.es/ecma262/#sec-asyncgeneratorunwrapyieldresumption
+//
+// Step 3.
+[[nodiscard]] static bool AsyncGeneratorYieldReturnAwaitedRejected(
+    JSContext* cx, Handle<AsyncGeneratorObject*> generator,
+    HandleValue reason) {
+  MOZ_ASSERT(
+      generator->isAwaitingYieldReturn(),
+      "YieldReturn-Await rejected when not in 'AwaitingYieldReturn' state");
+
+  // Step 3. If awaited.[[Type]] is throw, return Completion(awaited).
+  return AsyncGeneratorResume(cx, generator, CompletionKind::Throw, reason);
+}
+
+// ES2022 draft rev 193211a3d889a61e74ef7da1475dfa356e029f29
+//
+// AsyncGeneratorUnwrapYieldResumption ( resumptionValue )
+// https://tc39.es/ecma262/#sec-asyncgeneratorunwrapyieldresumption
+//
+// Steps 1-2.
+[[nodiscard]] static bool AsyncGeneratorUnwrapYieldResumptionAndResume(
+    JSContext* cx, Handle<AsyncGeneratorObject*> generator,
+    CompletionKind completionKind, HandleValue resumptionValue) {
+  // Step 1. If resumptionValue.[[Type]] is not return, return
+  //         Completion(resumptionValue).
+  if (completionKind != CompletionKind::Return) {
+    return AsyncGeneratorResume(cx, generator, completionKind, resumptionValue);
+  }
+
+  // Step 2. Let awaited be Await(resumptionValue.[[Value]]).
+  //
+  // Since we don't have the place that handles return from yield
+  // inside the generator, handle the case here, with extra state
+  // State_AwaitingYieldReturn.
+  generator->setAwaitingYieldReturn();
+
+  const PromiseHandler onFulfilled =
+      PromiseHandler::AsyncGeneratorYieldReturnAwaitedFulfilled;
+  const PromiseHandler onRejected =
+      PromiseHandler::AsyncGeneratorYieldReturnAwaitedRejected;
+
+  return InternalAsyncGeneratorAwait(cx, generator, resumptionValue,
+                                     onFulfilled, onRejected);
+}
+
+// ES2022 draft rev 193211a3d889a61e74ef7da1475dfa356e029f29
+//
+// AsyncGeneratorYield ( value )
+// https://tc39.es/ecma262/#sec-asyncgeneratoryield
+//
+// Stesp 10-13.
+[[nodiscard]] static bool AsyncGeneratorYield(
+    JSContext* cx, Handle<AsyncGeneratorObject*> generator, HandleValue value) {
+  // Step 10. Perform
+  //          ! AsyncGeneratorCompleteStep(generator, completion, false,
+  //                                       previousRealm).
+  if (!AsyncGeneratorCompleteStepNormal(cx, generator, value, false)) {
+    return false;
+  }
+
+  // Step 11. Let queue be generator.[[AsyncGeneratorQueue]].
+  // Step 12. If queue is not empty, then
+  // Step 13. Else,
+  // (reordered)
+  if (generator->isQueueEmpty()) {
+    // Step 13.a. Set generator.[[AsyncGeneratorState]] to suspendedYield.
+    generator->setSuspendedYield();
+
+    // Steps 13.b-c are done in caller.
+
+    // Step 13.d. Return undefined.
+    return true;
+  }
+
+  // Step 12. If queue is not empty, then
+  // Step 12.a. NOTE: Execution continues without suspending the generator.
+
+  // Step 12.b. Let toYield be the first element of queue.
+  Rooted<AsyncGeneratorRequest*> toYield(
+      cx, AsyncGeneratorObject::peekRequest(generator));
+  if (!toYield) {
+    return false;
+  }
+
+  // Step 12.c. Let resumptionValue be toYield.[[Completion]].
+  CompletionKind completionKind = toYield->completionKind();
+  RootedValue resumptionValue(cx, toYield->completionValue());
+
+  // Step 12.d. Return AsyncGeneratorUnwrapYieldResumption(resumptionValue).
+  return AsyncGeneratorUnwrapYieldResumptionAndResume(
+      cx, generator, completionKind, resumptionValue);
+}
+
+// ES2022 draft rev 193211a3d889a61e74ef7da1475dfa356e029f29
+//
+// Await in async function
+// https://tc39.es/ecma262/#await
+//
+// Steps 3.c-f.
+[[nodiscard]] static bool AsyncGeneratorAwaitedFulfilled(
+    JSContext* cx, Handle<AsyncGeneratorObject*> generator, HandleValue value) {
+  MOZ_ASSERT(generator->isExecuting(),
+             "Await fulfilled when not in 'Executing' state");
+
+  // Step 3.c. Push asyncContext onto the execution context stack; asyncContext
+  //           is now the running execution context.
+  // Step 3.d. Resume the suspended evaluation of asyncContext using
+  //           NormalCompletion(value) as the result of the operation that
+  //           suspended it.
+  // Step 3.f. Return undefined.
+  return AsyncGeneratorResume(cx, generator, CompletionKind::Normal, value);
+}
+
+// ES2022 draft rev 193211a3d889a61e74ef7da1475dfa356e029f29
+//
+// Await in async function
+// https://tc39.es/ecma262/#await
+//
+// Steps 5.c-f.
+[[nodiscard]] static bool AsyncGeneratorAwaitedRejected(
+    JSContext* cx, Handle<AsyncGeneratorObject*> generator,
+    HandleValue reason) {
+  MOZ_ASSERT(generator->isExecuting(),
+             "Await rejected when not in 'Executing' state");
+
+  // Step 5.c. Push asyncContext onto the execution context stack; asyncContext
+  //           is now the running execution context.
+  // Step 5.d. Resume the suspended evaluation of asyncContext using
+  //           ThrowCompletion(reason) as the result of the operation that
+  //           suspended it.
+  // Step 5.f. Return undefined.
+  return AsyncGeneratorResume(cx, generator, CompletionKind::Throw, reason);
+}
+
+// ES2022 draft rev 193211a3d889a61e74ef7da1475dfa356e029f29
+//
+// Await in async function
+// https://tc39.es/ecma262/#await
+[[nodiscard]] static bool AsyncGeneratorAwait(
+    JSContext* cx, Handle<AsyncGeneratorObject*> generator, HandleValue value) {
+  return InternalAsyncGeneratorAwait(
+      cx, generator, value, PromiseHandler::AsyncGeneratorAwaitedFulfilled,
+      PromiseHandler::AsyncGeneratorAwaitedRejected);
+}
+
+// ES2022 draft rev 193211a3d889a61e74ef7da1475dfa356e029f29
+//
+// AsyncGeneratorCompleteStep ( generator, completion, done [ , realm ] )
+// https://tc39.es/ecma262/#sec-asyncgeneratorcompletestep
+//
+// "normal" case.
+[[nodiscard]] static bool AsyncGeneratorCompleteStepNormal(
+    JSContext* cx, Handle<AsyncGeneratorObject*> generator, HandleValue value,
+    bool done) {
+  // Step 1. Let queue be generator.[[AsyncGeneratorQueue]].
+  // Step 2. Assert: queue is not empty.
+  MOZ_ASSERT(!generator->isQueueEmpty());
+
+  // Step 3. Let next be the first element of queue.
+  // Step 4. Remove the first element from queue.
+  AsyncGeneratorRequest* next =
+      AsyncGeneratorObject::dequeueRequest(cx, generator);
+  if (!next) {
+    return false;
+  }
+
+  // Step 5. Let promiseCapability be next.[[Capability]].
+  Rooted<PromiseObject*> resultPromise(cx, next->promise());
+
+  generator->cacheRequest(next);
+
+  // Step 6. Let value be completion.[[Value]].
+  // (passed by caller)
+
+  // Step 7. If completion.[[Type]] is throw, then
+  // Step 8. Else,
+  // Step 8.a. Assert: completion.[[Type]] is normal.
+
+  // Step 8.b. If realm is present, then
+  // (skipped)
+  // Step 8.c. Else,
+
+  // Step 8.c.i. Let iteratorResult be ! CreateIterResultObject(value, done).
+  JSObject* resultObj = CreateIterResultObject(cx, value, done);
+  if (!resultObj) {
+    return false;
+  }
+
+  // Step 8.d. Perform
+  //           ! Call(promiseCapability.[[Resolve]], undefined,
+  //                  « iteratorResult »).
+  RootedValue resultValue(cx, ObjectValue(*resultObj));
+  return ResolvePromiseInternal(cx, resultPromise, resultValue);
+}
+
+// ES2022 draft rev 193211a3d889a61e74ef7da1475dfa356e029f29
+//
+// AsyncGeneratorCompleteStep ( generator, completion, done [ , realm ] )
+// https://tc39.es/ecma262/#sec-asyncgeneratorcompletestep
+//
+// "throw" case.
+[[nodiscard]] static bool AsyncGeneratorCompleteStepThrow(
+    JSContext* cx, Handle<AsyncGeneratorObject*> generator,
+    HandleValue exception) {
+  // Step 1. Let queue be generator.[[AsyncGeneratorQueue]].
+  // Step 2. Assert: queue is not empty.
+  MOZ_ASSERT(!generator->isQueueEmpty());
+
+  // Step 3. Let next be the first element of queue.
+  // Step 4. Remove the first element from queue.
+  AsyncGeneratorRequest* next =
+      AsyncGeneratorObject::dequeueRequest(cx, generator);
+  if (!next) {
+    return false;
+  }
+
+  // Step 5. Let promiseCapability be next.[[Capability]].
+  Rooted<PromiseObject*> resultPromise(cx, next->promise());
+
+  generator->cacheRequest(next);
+
+  // Step 6. Let value be completion.[[Value]].
+  // (passed by caller)
+
+  // Step 7. If completion.[[Type]] is throw, then
+  // Step 7.a. Perform
+  //           ! Call(promiseCapability.[[Reject]], undefined, « value »).
+  return RejectPromiseInternal(cx, resultPromise, exception);
+}
+
+// ES2022 draft rev 193211a3d889a61e74ef7da1475dfa356e029f29
+//
+// AsyncGeneratorAwaitReturn ( generator )
+// https://tc39.es/ecma262/#sec-asyncgeneratorawaitreturn
+//
+// Steps 7.a-e.
+[[nodiscard]] static bool AsyncGeneratorAwaitReturnFulfilled(
+    JSContext* cx, Handle<AsyncGeneratorObject*> generator, HandleValue value) {
+  MOZ_ASSERT(generator->isAwaitingReturn(),
+             "AsyncGeneratorResumeNext-Return fulfilled when not in "
+             "'AwaitingReturn' state");
+
+  // Step 7.a. Set generator.[[AsyncGeneratorState]] to completed.
+  generator->setCompleted();
+
+  // Step 7.b. Let result be NormalCompletion(value).
+  // Step 7.c. Perform ! AsyncGeneratorCompleteStep(generator, result, true).
+  if (!AsyncGeneratorCompleteStepNormal(cx, generator, value, true)) {
+    return false;
+  }
+
+  // Step 7.d. Perform ! AsyncGeneratorDrainQueue(generator).
+  // Step 7.e. Return undefined.
+  return AsyncGeneratorDrainQueue(cx, generator);
+}
+
+// ES2022 draft rev 193211a3d889a61e74ef7da1475dfa356e029f29
+//
+// AsyncGeneratorAwaitReturn ( generator )
+// https://tc39.es/ecma262/#sec-asyncgeneratorawaitreturn
+//
+// Steps 9.a-e.
+[[nodiscard]] static bool AsyncGeneratorAwaitReturnRejected(
+    JSContext* cx, Handle<AsyncGeneratorObject*> generator, HandleValue value) {
+  MOZ_ASSERT(generator->isAwaitingReturn(),
+             "AsyncGeneratorResumeNext-Return rejected when not in "
+             "'AwaitingReturn' state");
+
+  // Step 9.a. Set generator.[[AsyncGeneratorState]] to completed.
+  generator->setCompleted();
+
+  // Step 9.b. Let result be ThrowCompletion(reason).
+  // Step 9.c. Perform ! AsyncGeneratorCompleteStep(generator, result, true).
+  if (!AsyncGeneratorCompleteStepThrow(cx, generator, value)) {
+    return false;
+  }
+
+  // Step 9.d. Perform ! AsyncGeneratorDrainQueue(generator).
+  // Step 9.e. Return undefined.
+  return AsyncGeneratorDrainQueue(cx, generator);
+}
+
+// ES2022 draft rev 193211a3d889a61e74ef7da1475dfa356e029f29
+//
+// AsyncGeneratorAwaitReturn ( generator )
+// https://tc39.es/ecma262/#sec-asyncgeneratorawaitreturn
+[[nodiscard]] static bool AsyncGeneratorAwaitReturn(
+    JSContext* cx, Handle<AsyncGeneratorObject*> generator, HandleValue next) {
+  // Step 1. Let queue be generator.[[AsyncGeneratorQueue]].
+  // Step 2. Assert: queue is not empty.
+  MOZ_ASSERT(!generator->isQueueEmpty());
+
+  // Step 3. Let next be the first element of queue.
+  // (passed by caller)
+
+  // Step 4. Let completion be next.[[Completion]].
+  // Step 5. Assert: completion.[[Type]] is return.
+  // (implicit)
+
+  // Steps 6-11.
+  return InternalAsyncGeneratorAwait(
+      cx, generator, next, PromiseHandler::AsyncGeneratorAwaitReturnFulfilled,
+      PromiseHandler::AsyncGeneratorAwaitReturnRejected);
+}
+
+// ES2022 draft rev 193211a3d889a61e74ef7da1475dfa356e029f29
+//
+// AsyncGeneratorDrainQueue ( generator )
+// https://tc39.es/ecma262/#sec-asyncgeneratordrainqueue
+[[nodiscard]] static bool AsyncGeneratorDrainQueue(
+    JSContext* cx, Handle<AsyncGeneratorObject*> generator) {
+  // Step 1. Assert: generator.[[AsyncGeneratorState]] is completed.
+  MOZ_ASSERT(generator->isCompleted());
+
+  // Step 2. Let queue be generator.[[AsyncGeneratorQueue]].
+  // Step 3. If queue is empty, return.
+  if (generator->isQueueEmpty()) {
+    return true;
+  }
+
+  // Step 4. Let done be false.
+  // (implicit)
+
+  // Step 5. Repeat, while done is false,
+  while (true) {
+    // Step 5.a. Let next be the first element of queue.
+    Rooted<AsyncGeneratorRequest*> next(
+        cx, AsyncGeneratorObject::peekRequest(generator));
+    if (!next) {
+      return false;
+    }
+
+    // Step 5.b. Let completion be next.[[Completion]].
+    CompletionKind completionKind = next->completionKind();
+
+    // Step 5.c. If completion.[[Type]] is return, then
+    if (completionKind == CompletionKind::Return) {
+      RootedValue value(cx, next->completionValue());
+
+      // Step 5.c.i. Set generator.[[AsyncGeneratorState]] to awaiting-return.
+      generator->setAwaitingReturn();
+
+      // Step 5.c.ii. Perform ! AsyncGeneratorAwaitReturn(generator).
+      // Step 5.c.iii. Set done to true.
+      return AsyncGeneratorAwaitReturn(cx, generator, value);
+    }
+
+    // Step 5.d. Else,
+    if (completionKind == CompletionKind::Throw) {
+      RootedValue value(cx, next->completionValue());
+
+      // Step 5.d.ii. Perform
+      //              ! AsyncGeneratorCompleteStep(generator, completion, true).
+      if (!AsyncGeneratorCompleteStepThrow(cx, generator, value)) {
+        return false;
+      }
+    } else {
+      // Step 5.d.i. If completion.[[Type]] is normal, then
+      // Step 5.d.i.1. Set completion to NormalCompletion(undefined).
+      // Step 5.d.ii. Perform
+      //              ! AsyncGeneratorCompleteStep(generator, completion, true).
+      if (!AsyncGeneratorCompleteStepNormal(cx, generator, UndefinedHandleValue,
+                                            true)) {
+        return false;
+      }
+    }
+
+    // Step 5.d.iii. If queue is empty, set done to true.
+    if (generator->isQueueEmpty()) {
+      return true;
+    }
+  }
+}
+
+// ES2022 draft rev 193211a3d889a61e74ef7da1475dfa356e029f29
+//
+// AsyncGeneratorValidate ( generator, generatorBrand )
+// https://tc39.es/ecma262/#sec-asyncgeneratorvalidate
+//
+// Testing part.
+[[nodiscard]] static bool IsAsyncGeneratorValid(HandleValue asyncGenVal) {
+  // Step 1. Perform
+  //         ? RequireInternalSlot(generator, [[AsyncGeneratorContext]]).
+  // Step 2. Perform
+  //         ? RequireInternalSlot(generator, [[AsyncGeneratorState]]).
+  // Step 3. Perform
+  //         ? RequireInternalSlot(generator, [[AsyncGeneratorQueue]]).
+  // Step 4. If generator.[[GeneratorBrand]] is not the same value as
+  //         generatorBrand, throw a TypeError exception.
+  return asyncGenVal.isObject() &&
+         asyncGenVal.toObject().canUnwrapAs<AsyncGeneratorObject>();
+}
+
+// ES2022 draft rev 193211a3d889a61e74ef7da1475dfa356e029f29
+//
+// AsyncGeneratorValidate ( generator, generatorBrand )
+// https://tc39.es/ecma262/#sec-asyncgeneratorvalidate
+//
+// Throwing part.
+[[nodiscard]] static bool AsyncGeneratorValidateThrow(
+    JSContext* cx, MutableHandleValue result) {
+  Rooted<PromiseObject*> resultPromise(
+      cx, CreatePromiseObjectForAsyncGenerator(cx));
+  if (!resultPromise) {
+    return false;
+  }
+
+  RootedValue badGeneratorError(cx);
+  if (!GetTypeError(cx, JSMSG_NOT_AN_ASYNC_GENERATOR, &badGeneratorError)) {
+    return false;
+  }
+
+  if (!RejectPromiseInternal(cx, resultPromise, badGeneratorError)) {
+    return false;
+  }
+
+  result.setObject(*resultPromise);
+  return true;
+}
+
+// ES2022 draft rev 193211a3d889a61e74ef7da1475dfa356e029f29
+//
+// AsyncGeneratorEnqueue ( generator, completion, promiseCapability )
+// https://tc39.es/ecma262/#sec-asyncgeneratorenqueue
+[[nodiscard]] static bool AsyncGeneratorEnqueue(
+    JSContext* cx, Handle<AsyncGeneratorObject*> generator,
+    CompletionKind completionKind, HandleValue completionValue,
+    Handle<PromiseObject*> resultPromise) {
+  // Step 1. Let request be
+  //         AsyncGeneratorRequest { [[Completion]]: completion,
+  //                                 [[Capability]]: promiseCapability }.
+  Rooted<AsyncGeneratorRequest*> request(
+      cx, AsyncGeneratorObject::createRequest(cx, generator, completionKind,
+                                              completionValue, resultPromise));
+  if (!request) {
+    return false;
+  }
+
+  // Step 2. Append request to the end of generator.[[AsyncGeneratorQueue]].
+  return AsyncGeneratorObject::enqueueRequest(cx, generator, request);
+}
+
+class MOZ_STACK_CLASS MaybeEnterAsyncGeneratorRealm {
+  mozilla::Maybe<AutoRealm> ar_;
+
+ public:
+  MaybeEnterAsyncGeneratorRealm() = default;
+  ~MaybeEnterAsyncGeneratorRealm() = default;
+
+  // Enter async generator's realm, and wrap the method's argument value if
+  // necessary.
+  [[nodiscard]] bool maybeEnterAndWrap(JSContext* cx,
+                                       Handle<AsyncGeneratorObject*> generator,
+                                       MutableHandleValue value) {
+    if (generator->compartment() == cx->compartment()) {
+      return true;
+    }
+
+    ar_.emplace(cx, generator);
+    return cx->compartment()->wrap(cx, value);
+  }
+
+  // Leave async generator's realm, and wrap the method's result value if
+  // necessary.
+  [[nodiscard]] bool maybeLeaveAndWrap(JSContext* cx,
+                                       MutableHandleValue result) {
+    if (!ar_) {
+      return true;
+    }
+    ar_.reset();
+
+    return cx->compartment()->wrap(cx, result);
+  }
+};
+
+[[nodiscard]] static bool AsyncGeneratorMethodSanityCheck(
+    JSContext* cx, Handle<AsyncGeneratorObject*> generator) {
+  if (generator->isCompleted() || generator->isSuspendedStart() ||
+      generator->isSuspendedYield()) {
+    // The spec assumes the queue is empty when async generator methods are
+    // called with those state, but our debugger allows calling those methods
+    // in unexpected state, such as before suspendedStart.
+    if (MOZ_UNLIKELY(!generator->isQueueEmpty())) {
+      JS_ReportErrorNumberASCII(cx, GetErrorMessage, nullptr,
+                                JSMSG_SUSPENDED_QUEUE_NOT_EMPTY);
+      return false;
+    }
+  }
+
+  return true;
+}
+
+// ES2022 draft rev 193211a3d889a61e74ef7da1475dfa356e029f29
+//
+// AsyncGenerator.prototype.next ( value )
+// https://tc39.es/ecma262/#sec-asyncgenerator-prototype-next
+bool js::AsyncGeneratorNext(JSContext* cx, unsigned argc, Value* vp) {
+  CallArgs args = CallArgsFromVp(argc, vp);
+
+  // Step 3. Let result be AsyncGeneratorValidate(generator, empty).
+  // Step 4. IfAbruptRejectPromise(result, promiseCapability).
+  // (reordered)
+  if (!IsAsyncGeneratorValid(args.thisv())) {
+    return AsyncGeneratorValidateThrow(cx, args.rval());
+  }
+
+  // Step 1. Let generator be the this value.
+  // (implicit)
+  Rooted<AsyncGeneratorObject*> generator(
+      cx, &args.thisv().toObject().unwrapAs<AsyncGeneratorObject>());
+
+  MaybeEnterAsyncGeneratorRealm maybeEnterRealm;
+
+  RootedValue completionValue(cx, args.get(0));
+  if (!maybeEnterRealm.maybeEnterAndWrap(cx, generator, &completionValue)) {
+    return false;
+  }
+
+  // Step 2. Let promiseCapability be ! NewPromiseCapability(%Promise%).
+  Rooted<PromiseObject*> resultPromise(
+      cx, CreatePromiseObjectForAsyncGenerator(cx));
+  if (!resultPromise) {
+    return false;
+  }
+
+  if (!AsyncGeneratorMethodSanityCheck(cx, generator)) {
+    return false;
+  }
+
+  // Step 5. Let state be generator.[[AsyncGeneratorState]].
+  // Step 6. If state is completed, then
+  if (generator->isCompleted()) {
+    // Step 6.a. Let iteratorResult be
+    //           ! CreateIterResultObject(undefined, true).
+    JSObject* resultObj =
+        CreateIterResultObject(cx, UndefinedHandleValue, true);
+    if (!resultObj) {
+      return false;
+    }
+
+    // Step 6.b. Perform
+    //           ! Call(promiseCapability.[[Resolve]], undefined,
+    //                  « iteratorResult »).
+    RootedValue resultValue(cx, ObjectValue(*resultObj));
+    if (!ResolvePromiseInternal(cx, resultPromise, resultValue)) {
+      return false;
+    }
+  } else {
+    // Step 7. Let completion be NormalCompletion(value).
+    // Step 8. Perform
+    //         ! AsyncGeneratorEnqueue(generator, completion,
+    //                                 promiseCapability).
+    if (!AsyncGeneratorEnqueue(cx, generator, CompletionKind::Normal,
+                               completionValue, resultPromise)) {
+      return false;
+    }
+
+    // Step 9. If state is either suspendedStart or suspendedYield, then
+    if (generator->isSuspendedStart() || generator->isSuspendedYield()) {
+      RootedValue resumptionValue(cx, completionValue);
+      // Step 9.a. Perform ! AsyncGeneratorResume(generator, completion).
+      if (!AsyncGeneratorResume(cx, generator, CompletionKind::Normal,
+                                resumptionValue)) {
+        return false;
+      }
+    } else {
+      // Step 10. Else,
+      // Step 10.a. Assert: state is either executing or awaiting-return.
+      MOZ_ASSERT(generator->isExecuting() || generator->isAwaitingReturn() ||
+                 generator->isAwaitingYieldReturn());
+    }
+  }
+
+  // Step 6.c. Return promiseCapability.[[Promise]].
+  // and
+  // Step 11. Return promiseCapability.[[Promise]].
+  args.rval().setObject(*resultPromise);
+
+  return maybeEnterRealm.maybeLeaveAndWrap(cx, args.rval());
+}
+
+// ES2022 draft rev 193211a3d889a61e74ef7da1475dfa356e029f29
+//
+// AsyncGenerator.prototype.return ( value )
+// https://tc39.es/ecma262/#sec-asyncgenerator-prototype-return
+bool js::AsyncGeneratorReturn(JSContext* cx, unsigned argc, Value* vp) {
+  CallArgs args = CallArgsFromVp(argc, vp);
+
+  // Step 3. Let result be AsyncGeneratorValidate(generator, empty).
+  // Step 4. IfAbruptRejectPromise(result, promiseCapability).
+  // (reordered)
+  if (!IsAsyncGeneratorValid(args.thisv())) {
+    return AsyncGeneratorValidateThrow(cx, args.rval());
+  }
+
+  // Step 1. Let generator be the this value.
+  Rooted<AsyncGeneratorObject*> generator(
+      cx, &args.thisv().toObject().unwrapAs<AsyncGeneratorObject>());
+
+  MaybeEnterAsyncGeneratorRealm maybeEnterRealm;
+
+  RootedValue completionValue(cx, args.get(0));
+  if (!maybeEnterRealm.maybeEnterAndWrap(cx, generator, &completionValue)) {
+    return false;
+  }
+
+  // Step 2. Let promiseCapability be ! NewPromiseCapability(%Promise%).
+  Rooted<PromiseObject*> resultPromise(
+      cx, CreatePromiseObjectForAsyncGenerator(cx));
+  if (!resultPromise) {
+    return false;
+  }
+
+  if (!AsyncGeneratorMethodSanityCheck(cx, generator)) {
+    return false;
+  }
+
+  // Step 5. Let completion be
+  //         Completion { [[Type]]: return, [[Value]]: value,
+  //                      [[Target]]: empty }.
+  // Step 6. Perform
+  //         ! AsyncGeneratorEnqueue(generator, completion, promiseCapability).
+  if (!AsyncGeneratorEnqueue(cx, generator, CompletionKind::Return,
+                             completionValue, resultPromise)) {
+    return false;
+  }
+
+  // Step 7. Let state be generator.[[AsyncGeneratorState]].
+  // Step 8. If state is either suspendedStart or completed, then
+  if (generator->isSuspendedStart() || generator->isCompleted()) {
+    // Step 8.a. Set generator.[[AsyncGeneratorState]] to awaiting-return.
+    generator->setAwaitingReturn();
+
+    // Step 8.b. Perform ! AsyncGeneratorAwaitReturn(generator).
+    if (!AsyncGeneratorAwaitReturn(cx, generator, completionValue)) {
+      return false;
+    }
+  } else if (generator->isSuspendedYield()) {
+    // Step 9. Else if state is suspendedYield, then
+
+    // Step 9.a. Perform ! AsyncGeneratorResume(generator, completion).
+    if (!AsyncGeneratorUnwrapYieldResumptionAndResume(
+            cx, generator, CompletionKind::Return, completionValue)) {
+      return false;
+    }
+  } else {
+    // Step 10. Else,
+    // Step 10.a. Assert: state is either executing or awaiting-return.
+    MOZ_ASSERT(generator->isExecuting() || generator->isAwaitingReturn() ||
+               generator->isAwaitingYieldReturn());
+  }
+
+  // Step 11. Return promiseCapability.[[Promise]].
+  args.rval().setObject(*resultPromise);
+
+  return maybeEnterRealm.maybeLeaveAndWrap(cx, args.rval());
+}
+
+// ES2022 draft rev 193211a3d889a61e74ef7da1475dfa356e029f29
+//
+// AsyncGenerator.prototype.throw ( exception )
+// https://tc39.es/ecma262/#sec-asyncgenerator-prototype-throw
+bool js::AsyncGeneratorThrow(JSContext* cx, unsigned argc, Value* vp) {
+  CallArgs args = CallArgsFromVp(argc, vp);
+
+  // Step 3. Let result be AsyncGeneratorValidate(generator, empty).
+  // Step 4. IfAbruptRejectPromise(result, promiseCapability).
+  // (reordered)
+  if (!IsAsyncGeneratorValid(args.thisv())) {
+    return AsyncGeneratorValidateThrow(cx, args.rval());
+  }
+
+  // Step 1. Let generator be the this value.
+  Rooted<AsyncGeneratorObject*> generator(
+      cx, &args.thisv().toObject().unwrapAs<AsyncGeneratorObject>());
+
+  MaybeEnterAsyncGeneratorRealm maybeEnterRealm;
+
+  RootedValue completionValue(cx, args.get(0));
+  if (!maybeEnterRealm.maybeEnterAndWrap(cx, generator, &completionValue)) {
+    return false;
+  }
+
+  // Step 2. Let promiseCapability be ! NewPromiseCapability(%Promise%).
+  Rooted<PromiseObject*> resultPromise(
+      cx, CreatePromiseObjectForAsyncGenerator(cx));
+  if (!resultPromise) {
+    return false;
+  }
+
+  if (!AsyncGeneratorMethodSanityCheck(cx, generator)) {
+    return false;
+  }
+
+  // Step 5. Let state be generator.[[AsyncGeneratorState]].
+  // Step 6. If state is suspendedStart, then
+  if (generator->isSuspendedStart()) {
+    // Step 6.a. Set generator.[[AsyncGeneratorState]] to completed.
+    // Step 6.b. Set state to completed.
+    generator->setCompleted();
+  }
+
+  // Step 7. If state is completed, then
+  if (generator->isCompleted()) {
+    // Step 7.a. Perform
+    //           ! Call(promiseCapability.[[Reject]], undefined, « exception »).
+    if (!RejectPromiseInternal(cx, resultPromise, completionValue)) {
+      return false;
+    }
+  } else {
+    // Step 8. Let completion be ThrowCompletion(exception).
+    // Step 9. Perform
+    //         ! AsyncGeneratorEnqueue(generator, completion,
+    //                                 promiseCapability).
+    if (!AsyncGeneratorEnqueue(cx, generator, CompletionKind::Throw,
+                               completionValue, resultPromise)) {
+      return false;
+    }
+
+    // Step 10. If state is suspendedYield, then
+    if (generator->isSuspendedYield()) {
+      // Step 10.a. Perform ! AsyncGeneratorResume(generator, completion).
+      if (!AsyncGeneratorResume(cx, generator, CompletionKind::Throw,
+                                completionValue)) {
+        return false;
+      }
+    } else {
+      // Step 11. Else,
+      // Step 11.a. Assert: state is either executing or awaiting-return.
+      MOZ_ASSERT(generator->isExecuting() || generator->isAwaitingReturn() ||
+                 generator->isAwaitingYieldReturn());
+    }
+  }
+
+  // Step 7.b. Return promiseCapability.[[Promise]].
+  // and
+  // Step 12. Return promiseCapability.[[Promise]].
+  args.rval().setObject(*resultPromise);
+
+  return maybeEnterRealm.maybeLeaveAndWrap(cx, args.rval());
+}
+
+// ES2022 draft rev 193211a3d889a61e74ef7da1475dfa356e029f29
+//
+// AsyncGeneratorResume ( generator, completion )
+// https://tc39.es/ecma262/#sec-asyncgeneratorresume
+[[nodiscard]] static bool AsyncGeneratorResume(
+    JSContext* cx, Handle<AsyncGeneratorObject*> generator,
+    CompletionKind completionKind, HandleValue argument) {
+  MOZ_ASSERT(!generator->isClosed(),
+             "closed generator when resuming async generator");
+  MOZ_ASSERT(generator->isSuspended(),
+             "non-suspended generator when resuming async generator");
+
+  // Step 1. Assert: generator.[[AsyncGeneratorState]] is either
+  //         suspendedStart or suspendedYield.
+  //
+  // NOTE: We're using suspend/resume also for await. and the state can be
+  //       anything.
+
+  // Steps 2-4 are handled in generator.
+
+  // Step 5. Set generator.[[AsyncGeneratorState]] to executing.
+  generator->setExecuting();
+
+  // Step 6. Push genContext onto the execution context stack; genContext is
+  //         now the running execution context.
+  // Step 7. Resume the suspended evaluation of genContext using completion as
+  //         the result of the operation that suspended it. Let result be the
+  //         completion record returned by the resumed computation.
+  Handle<PropertyName*> funName = completionKind == CompletionKind::Normal
+                                      ? cx->names().AsyncGeneratorNext
+                                  : completionKind == CompletionKind::Throw
+                                      ? cx->names().AsyncGeneratorThrow
+                                      : cx->names().AsyncGeneratorReturn;
+  FixedInvokeArgs<1> args(cx);
+  args[0].set(argument);
+  RootedValue thisOrRval(cx, ObjectValue(*generator));
+  if (!CallSelfHostedFunction(cx, funName, thisOrRval, args, &thisOrRval)) {
+    // 25.5.3.2, steps 5.f, 5.g.
+    if (!generator->isClosed()) {
+      generator->setClosed();
+    }
+    return AsyncGeneratorThrown(cx, generator);
+  }
+
+  // 6.2.3.1, steps 2-9.
+  if (generator->isAfterAwait()) {
+    return AsyncGeneratorAwait(cx, generator, thisOrRval);
+  }
+
+  // 25.5.3.7, steps 5-6, 9.
+  if (generator->isAfterYield()) {
+    return AsyncGeneratorYield(cx, generator, thisOrRval);
+  }
+
+  // 25.5.3.2, steps 5.d-g.
+  return AsyncGeneratorReturned(cx, generator, thisOrRval);
+}
+
+static const JSFunctionSpec async_generator_methods[] = {
+    JS_FN("next", js::AsyncGeneratorNext, 1, 0),
+    JS_FN("throw", js::AsyncGeneratorThrow, 1, 0),
+    JS_FN("return", js::AsyncGeneratorReturn, 1, 0), JS_FS_END};
+
+static JSObject* CreateAsyncGeneratorFunction(JSContext* cx, JSProtoKey key) {
+  RootedObject proto(cx, &cx->global()->getFunctionConstructor());
+  Handle<PropertyName*> name = cx->names().AsyncGeneratorFunction;
+
+  // ES2022 draft rev 193211a3d889a61e74ef7da1475dfa356e029f29
+  //
+  // The AsyncGeneratorFunction Constructor
+  // https://tc39.es/ecma262/#sec-asyncgeneratorfunction-constructor
+  return NewFunctionWithProto(cx, AsyncGeneratorConstructor, 1,
+                              FunctionFlags::NATIVE_CTOR, nullptr, name, proto,
+                              gc::AllocKind::FUNCTION, TenuredObject);
+}
+
+static JSObject* CreateAsyncGeneratorFunctionPrototype(JSContext* cx,
+                                                       JSProtoKey key) {
+  return NewTenuredObjectWithFunctionPrototype(cx, cx->global());
+}
+
+static bool AsyncGeneratorFunctionClassFinish(JSContext* cx,
+                                              HandleObject asyncGenFunction,
+                                              HandleObject asyncGenerator) {
+  Handle<GlobalObject*> global = cx->global();
+
+  // Change the "constructor" property to non-writable before adding any other
+  // properties, so it's still the last property and can be modified without a
+  // dictionary-mode transition.
+  MOZ_ASSERT(asyncGenerator->as<NativeObject>().getLastProperty().key() ==
+             NameToId(cx->names().constructor));
+  MOZ_ASSERT(!asyncGenerator->as<NativeObject>().inDictionaryMode());
+
+  RootedValue asyncGenFunctionVal(cx, ObjectValue(*asyncGenFunction));
+  if (!DefineDataProperty(cx, asyncGenerator, cx->names().constructor,
+                          asyncGenFunctionVal, JSPROP_READONLY)) {
+    return false;
+  }
+  MOZ_ASSERT(!asyncGenerator->as<NativeObject>().inDictionaryMode());
+
+  RootedObject asyncIterProto(
+      cx, GlobalObject::getOrCreateAsyncIteratorPrototype(cx, global));
+  if (!asyncIterProto) {
+    return false;
+  }
+
+  // ES2022 draft rev 193211a3d889a61e74ef7da1475dfa356e029f29
+  //
+  // AsyncGenerator Objects
+  // https://tc39.es/ecma262/#sec-asyncgenerator-objects
+  RootedObject asyncGenProto(cx, GlobalObject::createBlankPrototypeInheriting(
+                                     cx, &PlainObject::class_, asyncIterProto));
+  if (!asyncGenProto) {
+    return false;
+  }
+  if (!DefinePropertiesAndFunctions(cx, asyncGenProto, nullptr,
+                                    async_generator_methods) ||
+      !DefineToStringTag(cx, asyncGenProto, cx->names().AsyncGenerator)) {
+    return false;
+  }
+
+  // ES2022 draft rev 193211a3d889a61e74ef7da1475dfa356e029f29
+  //
+  // Properties of the AsyncGeneratorFunction Prototype Object
+  // https://tc39.es/ecma262/#sec-properties-of-asyncgeneratorfunction-prototype
+  if (!LinkConstructorAndPrototype(cx, asyncGenerator, asyncGenProto,
+                                   JSPROP_READONLY, JSPROP_READONLY) ||
+      !DefineToStringTag(cx, asyncGenerator,
+                         cx->names().AsyncGeneratorFunction)) {
+    return false;
+  }
+
+  global->setAsyncGeneratorPrototype(asyncGenProto);
+
+  return true;
+}
+
+static const ClassSpec AsyncGeneratorFunctionClassSpec = {
+    CreateAsyncGeneratorFunction,
+    CreateAsyncGeneratorFunctionPrototype,
+    nullptr,
+    nullptr,
+    nullptr,
+    nullptr,
+    AsyncGeneratorFunctionClassFinish,
+    ClassSpec::DontDefineConstructor};
+
+const JSClass js::AsyncGeneratorFunctionClass = {
+    "AsyncGeneratorFunction", 0, JS_NULL_CLASS_OPS,
+    &AsyncGeneratorFunctionClassSpec};
+
+[[nodiscard]] bool js::AsyncGeneratorPromiseReactionJob(
+    JSContext* cx, PromiseHandler handler,
+    Handle<AsyncGeneratorObject*> generator, HandleValue argument) {
+  // Await's handlers don't return a value, nor throw any exceptions.
+  // They fail only on OOM.
+  switch (handler) {
+    case PromiseHandler::AsyncGeneratorAwaitedFulfilled:
+      return AsyncGeneratorAwaitedFulfilled(cx, generator, argument);
+
+    case PromiseHandler::AsyncGeneratorAwaitedRejected:
+      return AsyncGeneratorAwaitedRejected(cx, generator, argument);
+
+    case PromiseHandler::AsyncGeneratorAwaitReturnFulfilled:
+      return AsyncGeneratorAwaitReturnFulfilled(cx, generator, argument);
+
+    case PromiseHandler::AsyncGeneratorAwaitReturnRejected:
+      return AsyncGeneratorAwaitReturnRejected(cx, generator, argument);
+
+    case PromiseHandler::AsyncGeneratorYieldReturnAwaitedFulfilled:
+      return AsyncGeneratorYieldReturnAwaitedFulfilled(cx, generator, argument);
+
+    case PromiseHandler::AsyncGeneratorYieldReturnAwaitedRejected:
+      return AsyncGeneratorYieldReturnAwaitedRejected(cx, generator, argument);
+
+    default:
+      MOZ_CRASH("Bad handler in AsyncGeneratorPromiseReactionJob");
+  }
+}
+
+// ---------------------
+// AsyncFromSyncIterator
+// ---------------------
+
+const JSClass AsyncFromSyncIteratorObject::class_ = {
+    "AsyncFromSyncIteratorObject",
+    JSCLASS_HAS_RESERVED_SLOTS(AsyncFromSyncIteratorObject::Slots)};
+
+/*
+ * ES2024 draft rev 53454a9a596d90473d2152ef04656d605162cd4c
+ *
+ * CreateAsyncFromSyncIterator ( syncIteratorRecord )
+ * https://tc39.es/ecma262/#sec-createasyncfromsynciterator
+ */
+JSObject* js::CreateAsyncFromSyncIterator(JSContext* cx, HandleObject iter,
+                                          HandleValue nextMethod) {
+  // Steps 1-5.
+  return AsyncFromSyncIteratorObject::create(cx, iter, nextMethod);
+}
+
+/*
+ * ES2024 draft rev 53454a9a596d90473d2152ef04656d605162cd4c
+ *
+ * CreateAsyncFromSyncIterator ( syncIteratorRecord )
+ * https://tc39.es/ecma262/#sec-createasyncfromsynciterator
+ */
+/* static */
+JSObject* AsyncFromSyncIteratorObject::create(JSContext* cx, HandleObject iter,
+                                              HandleValue nextMethod) {
+  // Step 1. Let asyncIterator be
+  //         OrdinaryObjectCreate(%AsyncFromSyncIteratorPrototype%, «
+  //         [[SyncIteratorRecord]] »).
+  RootedObject proto(cx,
+                     GlobalObject::getOrCreateAsyncFromSyncIteratorPrototype(
+                         cx, cx->global()));
+  if (!proto) {
+    return nullptr;
+  }
+
+  AsyncFromSyncIteratorObject* asyncIter =
+      NewObjectWithGivenProto<AsyncFromSyncIteratorObject>(cx, proto);
+  if (!asyncIter) {
+    return nullptr;
+  }
+
+  // Step 3. Let nextMethod be ! Get(asyncIterator, "next").
+  // (done in caller)
+
+  // Step 2. Set asyncIterator.[[SyncIteratorRecord]] to syncIteratorRecord.
+  // Step 4. Let iteratorRecord be the Iterator Record { [[Iterator]]:
+  //         asyncIterator, [[NextMethod]]: nextMethod, [[Done]]: false }.
+  asyncIter->init(iter, nextMethod);
+
+  // Step 5. Return iteratorRecord.
+  return asyncIter;
+}
+
+/**
+ * ES2024 draft rev 53454a9a596d90473d2152ef04656d605162cd4c
+ *
+ * %AsyncFromSyncIteratorPrototype%.next ( [ value ] )
+ * https://tc39.es/ecma262/#sec-%asyncfromsynciteratorprototype%.next
+ */
+static bool AsyncFromSyncIteratorNext(JSContext* cx, unsigned argc, Value* vp) {
+  CallArgs args = CallArgsFromVp(argc, vp);
+  return AsyncFromSyncIteratorMethod(cx, args, CompletionKind::Normal);
+}
+
+/**
+ * ES2024 draft rev 53454a9a596d90473d2152ef04656d605162cd4c
+ *
+ * %AsyncFromSyncIteratorPrototype%.return ( [ value ] )
+ * https://tc39.es/ecma262/#sec-%asyncfromsynciteratorprototype%.return
+ */
+static bool AsyncFromSyncIteratorReturn(JSContext* cx, unsigned argc,
+                                        Value* vp) {
+  CallArgs args = CallArgsFromVp(argc, vp);
+  return AsyncFromSyncIteratorMethod(cx, args, CompletionKind::Return);
+}
+
+/**
+ * ES2024 draft rev 53454a9a596d90473d2152ef04656d605162cd4c
+ *
+ * %AsyncFromSyncIteratorPrototype%.throw ( [ value ] )
+ * https://tc39.es/ecma262/#sec-%asyncfromsynciteratorprototype%.throw
+ */
+static bool AsyncFromSyncIteratorThrow(JSContext* cx, unsigned argc,
+                                       Value* vp) {
+  CallArgs args = CallArgsFromVp(argc, vp);
+  return AsyncFromSyncIteratorMethod(cx, args, CompletionKind::Throw);
+}
+
+static const JSFunctionSpec async_from_sync_iter_methods[] = {
+    JS_FN("next", AsyncFromSyncIteratorNext, 1, 0),
+    JS_FN("throw", AsyncFromSyncIteratorThrow, 1, 0),
+    JS_FN("return", AsyncFromSyncIteratorReturn, 1, 0), JS_FS_END};
+
+bool GlobalObject::initAsyncFromSyncIteratorProto(
+    JSContext* cx, Handle<GlobalObject*> global) {
+  if (global->hasBuiltinProto(ProtoKind::AsyncFromSyncIteratorProto)) {
+    return true;
+  }
+
+  RootedObject asyncIterProto(
+      cx, GlobalObject::getOrCreateAsyncIteratorPrototype(cx, global));
+  if (!asyncIterProto) {
+    return false;
+  }
+
+  // ES2024 draft rev 53454a9a596d90473d2152ef04656d605162cd4c
+  //
+  // The %AsyncFromSyncIteratorPrototype% Object
+  // https://tc39.es/ecma262/#sec-%asyncfromsynciteratorprototype%-object
+  RootedObject asyncFromSyncIterProto(
+      cx, GlobalObject::createBlankPrototypeInheriting(cx, &PlainObject::class_,
+                                                       asyncIterProto));
+  if (!asyncFromSyncIterProto) {
+    return false;
+  }
+  if (!DefinePropertiesAndFunctions(cx, asyncFromSyncIterProto, nullptr,
+                                    async_from_sync_iter_methods) ||
+      !DefineToStringTag(cx, asyncFromSyncIterProto,
+                         cx->names().Async_from_Sync_Iterator_)) {
+    return false;
+  }
+
+  global->initBuiltinProto(ProtoKind::AsyncFromSyncIteratorProto,
+                           asyncFromSyncIterProto);
+  return true;
+}
+
+// -------------
+// AsyncIterator
+// -------------
+
+static const JSFunctionSpec async_iterator_proto_methods[] = {
+    JS_SELF_HOSTED_SYM_FN(asyncIterator, "AsyncIteratorIdentity", 0, 0),
+    JS_FS_END};
+
+static const JSFunctionSpec async_iterator_proto_methods_with_helpers[] = {
+    JS_SELF_HOSTED_FN("map", "AsyncIteratorMap", 1, 0),
+    JS_SELF_HOSTED_FN("filter", "AsyncIteratorFilter", 1, 0),
+    JS_SELF_HOSTED_FN("take", "AsyncIteratorTake", 1, 0),
+    JS_SELF_HOSTED_FN("drop", "AsyncIteratorDrop", 1, 0),
+    JS_SELF_HOSTED_FN("asIndexedPairs", "AsyncIteratorAsIndexedPairs", 0, 0),
+    JS_SELF_HOSTED_FN("flatMap", "AsyncIteratorFlatMap", 1, 0),
+    JS_SELF_HOSTED_FN("reduce", "AsyncIteratorReduce", 1, 0),
+    JS_SELF_HOSTED_FN("toArray", "AsyncIteratorToArray", 0, 0),
+    JS_SELF_HOSTED_FN("forEach", "AsyncIteratorForEach", 1, 0),
+    JS_SELF_HOSTED_FN("some", "AsyncIteratorSome", 1, 0),
+    JS_SELF_HOSTED_FN("every", "AsyncIteratorEvery", 1, 0),
+    JS_SELF_HOSTED_FN("find", "AsyncIteratorFind", 1, 0),
+    JS_SELF_HOSTED_SYM_FN(asyncIterator, "AsyncIteratorIdentity", 0, 0),
+    JS_FS_END};
+
+bool GlobalObject::initAsyncIteratorProto(JSContext* cx,
+                                          Handle<GlobalObject*> global) {
+  if (global->hasBuiltinProto(ProtoKind::AsyncIteratorProto)) {
+    return true;
+  }
+
+  // 25.1.3 The %AsyncIteratorPrototype% Object
+  RootedObject asyncIterProto(
+      cx, GlobalObject::createBlankPrototype<PlainObject>(cx, global));
+  if (!asyncIterProto) {
+    return false;
+  }
+  if (!DefinePropertiesAndFunctions(cx, asyncIterProto, nullptr,
+                                    async_iterator_proto_methods)) {
+    return false;
+  }
+
+  global->initBuiltinProto(ProtoKind::AsyncIteratorProto, asyncIterProto);
+  return true;
+}
+
+// https://tc39.es/proposal-iterator-helpers/#sec-asynciterator as of revision
+// 8f10db5.
+static bool AsyncIteratorConstructor(JSContext* cx, unsigned argc, Value* vp) {
+  CallArgs args = CallArgsFromVp(argc, vp);
+
+  // Step 1.
+  if (!ThrowIfNotConstructing(cx, args, "AsyncIterator")) {
+    return false;
+  }
+  // Throw TypeError if NewTarget is the active function object, preventing the
+  // Iterator constructor from being used directly.
+  if (args.callee() == args.newTarget().toObject()) {
+    JS_ReportErrorNumberASCII(cx, GetErrorMessage, nullptr,
+                              JSMSG_BOGUS_CONSTRUCTOR, "AsyncIterator");
+    return false;
+  }
+
+  // Step 2.
+  RootedObject proto(cx);
+  if (!GetPrototypeFromBuiltinConstructor(cx, args, JSProto_AsyncIterator,
+                                          &proto)) {
+    return false;
+  }
+
+  JSObject* obj = NewObjectWithClassProto<AsyncIteratorObject>(cx, proto);
+  if (!obj) {
+    return false;
+  }
+
+  args.rval().setObject(*obj);
+  return true;
+}
+
+static const ClassSpec AsyncIteratorObjectClassSpec = {
+    GenericCreateConstructor<AsyncIteratorConstructor, 0,
+                             gc::AllocKind::FUNCTION>,
+    GenericCreatePrototype<AsyncIteratorObject>,
+    nullptr,
+    nullptr,
+    async_iterator_proto_methods_with_helpers,
+    nullptr,
+    nullptr,
+};
+
+const JSClass AsyncIteratorObject::class_ = {
+    "AsyncIterator",
+    JSCLASS_HAS_CACHED_PROTO(JSProto_AsyncIterator),
+    JS_NULL_CLASS_OPS,
+    &AsyncIteratorObjectClassSpec,
+};
+
+const JSClass AsyncIteratorObject::protoClass_ = {
+    "AsyncIterator.prototype",
+    JSCLASS_HAS_CACHED_PROTO(JSProto_AsyncIterator),
+    JS_NULL_CLASS_OPS,
+    &AsyncIteratorObjectClassSpec,
+};
+
+// Iterator Helper proposal
+static const JSFunctionSpec async_iterator_helper_methods[] = {
+    JS_SELF_HOSTED_FN("next", "AsyncIteratorHelperNext", 1, 0),
+    JS_SELF_HOSTED_FN("return", "AsyncIteratorHelperReturn", 1, 0),
+    JS_SELF_HOSTED_FN("throw", "AsyncIteratorHelperThrow", 1, 0),
+    JS_FS_END,
+};
+
+static const JSClass AsyncIteratorHelperPrototypeClass = {
+    "Async Iterator Helper", 0};
+
+const JSClass AsyncIteratorHelperObject::class_ = {
+    "Async Iterator Helper",
+    JSCLASS_HAS_RESERVED_SLOTS(AsyncIteratorHelperObject::SlotCount),
+};
+
+/* static */
+NativeObject* GlobalObject::getOrCreateAsyncIteratorHelperPrototype(
+    JSContext* cx, Handle<GlobalObject*> global) {
+  return MaybeNativeObject(
+      getOrCreateBuiltinProto(cx, global, ProtoKind::AsyncIteratorHelperProto,
+                              initAsyncIteratorHelperProto));
+}
+
+/* static */
+bool GlobalObject::initAsyncIteratorHelperProto(JSContext* cx,
+                                                Handle<GlobalObject*> global) {
+  if (global->hasBuiltinProto(ProtoKind::AsyncIteratorHelperProto)) {
+    return true;
+  }
+
+  RootedObject asyncIterProto(
+      cx, GlobalObject::getOrCreateAsyncIteratorPrototype(cx, global));
+  if (!asyncIterProto) {
+    return false;
+  }
+
+  RootedObject asyncIteratorHelperProto(
+      cx, GlobalObject::createBlankPrototypeInheriting(
+              cx, &AsyncIteratorHelperPrototypeClass, asyncIterProto));
+  if (!asyncIteratorHelperProto) {
+    return false;
+  }
+  if (!DefinePropertiesAndFunctions(cx, asyncIteratorHelperProto, nullptr,
+                                    async_iterator_helper_methods)) {
+    return false;
+  }
+
+  global->initBuiltinProto(ProtoKind::AsyncIteratorHelperProto,
+                           asyncIteratorHelperProto);
+  return true;
+}
+
+AsyncIteratorHelperObject* js::NewAsyncIteratorHelper(JSContext* cx) {
+  RootedObject proto(cx, GlobalObject::getOrCreateAsyncIteratorHelperPrototype(
+                             cx, cx->global()));
+  if (!proto) {
+    return nullptr;
+  }
+  return NewObjectWithGivenProto<AsyncIteratorHelperObject>(cx, proto);
+}