weakrefchecklist.txt

The WeakRef Constructor
https://tc39.github.io/proposal-weakrefs/#sec-weak-ref-constructor

- [ ] is the initial value of the WeakRef property of the global object.
- [ ] is designed to be subclassable. It may be used as the value in an extends clause of a class definition. Subclass constructors that intend to inherit the specified WeakRef behaviour must include a super call to the WeakRef constructor to create and initialize the subclass instance with the internal state necessary to support the  WeakRef.prototype built-in methods.

WeakRef ( target )
https://tc39.github.io/proposal-weakrefs/#sec-weak-ref-target

1. [ ] If NewTarget is undefined, throw a TypeError exception.
2. [ ] If Type(target) is not Object, throw a TypeError exception.
3. [ ] Let weakRef be ? OrdinaryCreateFromConstructor(NewTarget,  "%WeakRefPrototype%", « [[Target]] »).
4. Perfom ! KeepDuringJob(target).
5. Set weakRef.[[Target]] to target.
6. [ ] Return weakRef.

Properties of the WeakRef Constructor
https://tc39.github.io/proposal-weakrefs/#sec-properties-of-the-weak-ref-constructor

- [ ] has a [[Prototype]] internal slot whose value is the intrinsic object %FunctionPrototype%.

WeakRef.prototype
https://tc39.github.io/proposal-weakrefs/#sec-weak-ref.prototype

- [ ] This property has the attributes { [[Writable]]: false, [[Enumerable]]: false, [[Configurable]]: false }.

Properties of the WeakRef Prototype Object

- [ ] has a [[Prototype]] internal slot whose value is the intrinsic object %ObjectPrototype%.
- [ ] does not have a [[Target]] internal slot.

WeakRef.prototype.deref ( )
https://tc39.github.io/proposal-weakrefs/#sec-weak-ref.prototype.deref

1. Let weakRef be the this value.
2. [ ] If Type(weakRef) is not Object, throw a TypeError exception.
3. [ ] If weakRef does not have a [[Target]] internal slot, throw a TypeError exception.
4. Let target be the value of weakRef.[[Target]].
5. [ ] If target is not empty,
  a. Perform ! KeepDuringJob(target).
  b. [ ] Return target.
6. [ ] Return undefined.

WeakRef.prototype [ @@toStringTag ]
https://tc39.github.io/proposal-weakrefs/#sec-weak-ref.prototype-@@tostringtag

- [ ] The initial value of the @@toStringTag property is the String value "WeakRef".
- [ ] This property has the attributes { [[Writable]]: false, [[Enumerable]]: false, [[Configurable]]: true }.

The FinalizationGroup Constructor
https://tc39.github.io/proposal-weakrefs/#sec-finalization-group-constructor

- [ ] is the initial value of the FinalizationGroup property of the global object.

FinalizationGroup ( cleanupCallback )
https://tc39.github.io/proposal-weakrefs/#sec-finalization-group-cleanup-callback

1. [ ] If NewTarget is undefined, throw a TypeError exception.
2. [ ] If IsCallable(cleanupCallback) is false, throw a TypeError exception.
3. [ ] Let finalizationGroup be ? OrdinaryCreateFromConstructor(NewTarget,  "%FinalizationGroupPrototype%", « [[Realm]], [[CleanupCallback]], [[Cells]], [[IsFinalizationGroupCleanupJobActive]] »).
4. Let fn be the active function object.
5. Set finalizationGroup.[[Realm]] to fn.[[Realm]].
6. Set finalizationGroup.[[CleanupCallback]] to cleanupCallback.
7. Set finalizationGroup.[[Cells]] to be an empty List.
8. Set finalizationGroup.[[IsFinalizationGroupCleanupJobActive]] to false.
9. [ ] Return finalizationGroup.

Properties of the FinalizationGroup Constructor
https://tc39.github.io/proposal-weakrefs/#sec-properties-of-the-finalization-group-constructor

- [ ] has a [[Prototype]] internal slot whose value is the intrinsic object %FunctionPrototype%.

FinalizationGroup.prototype
https://tc39.github.io/proposal-weakrefs/#sec-finalization-group.prototype

- [ ] This property has the attributes { [[Writable]]: false, [[Enumerable]]: false, [[Configurable]]: false }.

Properties of the FinalizationGroup Prototype Object
https://tc39.github.io/proposal-weakrefs/#sec-properties-of-the-finalization-group-prototype-object

- [ ] has a [[Prototype]] internal slot whose value is the intrinsic object %ObjectPrototype%.
is an ordinary object.
- [ ] does not have a [[Target]] internal slot.

FinalizationGroup.prototype.constructor
https://tc39.github.io/proposal-weakrefs/#sec-finalization-group.prototype.constructor

- [ ] The initial value of  FinalizationGroup.prototype.constructor is the intrinsic object %FinalizationGroup%.

FinalizationGroup.prototype.register ( target , holdings [, unregisterToken ] )
https://tc39.github.io/proposal-weakrefs/#sec-finalization-group.prototype.register 

1. Let finalizationGroup be the this value.
2. [ ] If Type(finalizationGroup) is not Object, throw a TypeError exception.
3. [ ] If Type(target) is not Object, throw a TypeError exception.
4. [ ] If finalizationGroup does not have a [[Cells]] internal slot, throw a TypeError exception.
5. If Type(unregisterToken) is not Object,
  a. [ ] If unregisterToken is not undefined, throw a TypeError exception.
  b. [ ] Set unregisterToken to empty.
6. Let cell be the Record { [[Target]] : target, [[Holdings]]: holdings, [[UnregisterToken]]: unregisterToken }.
7. Append cell to finalizationGroup.[[Cells]].
8. [ ] Return undefined.

FinalizationGroup.prototype.unregister ( unregisterToken )
https://tc39.github.io/proposal-weakrefs/#sec-finalization-group.prototype.unregister 

1. Let finalizationGroup be the this value.
2. [ ] If Type(finalizationGroup) is not Object, throw a TypeError exception.
3. [ ] If finalizationGroup does not have a [[Cells]] internal slot, throw a TypeError exception.
4. [ ] If Type(unregisterToken) is not Object, through a TypeError exception.
5. Let removed be false.
6. For each Record { [[Target]], [[Holdings]], [[UnregisterToken]] } cell that is an element of finalizationGroup.[[Cells]], do
  a. If SameValue(cell.[[UnregisterToken]], unregisterToken) is true, then
    i. Remove cell from finalizationGroup.[[Cells]].
    ii. Set removed to true.
7. [ ] Return removed.

FinalizationGroup.prototype.cleanupSome ( [ callback ] )
https://tc39.github.io/proposal-weakrefs/#sec-finalization-group.prototype.cleanupSome

1. Let finalizationGroup be the this value.
2. [ ] If Type(finalizationGroup) is not Object, throw a TypeError exception.
3. [ ] If finalizationGroup does not have a [[Cells]] internal slot, throw a TypeError exception.
4. [ ] If callback is not undefined and IsCallable(callback) is false, throw a TypeError exception.
5. Perform ! CleanupFinalizationGroup(finalizationGroup, callback).
6. [ ] Return undefined.

FinalizationGroup.prototype [ @@toStringTag ]
https://tc39.github.io/proposal-weakrefs/#sec-finalization-group.prototype-@@tostringtag

- [ ] The initial value of the @@toStringTag property is the String value "FinalizationGroup".
- [ ] This property has the attributes { [[Writable]]: false, [[Enumerable]]: false, [[Configurable]]: true }.

CreateFinalizationGroupCleanupIterator ( finalizationGroup )
https://tc39.github.io/proposal-weakrefs/#sec-createfinalizationgroupcleanupiterator

1.  Let finalizationGroup be the this value.
2. [ ] If Type(finalizationGroup) is not Object, throw a TypeError exception.
3. [ ] If finalizationGroup does not have a [[Cells]] internal slot, throw a TypeError exception.
4. Assert: realm.[[Intrinsics]].[[%FinalizationGroupCleanupIteratorPrototype%]] exists and has been initialized.
5. Let prototype be finalizationGroup.[[Realm]].[[Intrinsics]].[[%FinalizationGroupCleanupIteratorPrototype%]].
6. Let iterator be ObjectCreate(prototype, « [[FinalizationGroup]] »).
7. Set iterator.[[FinalizationGroup]] to finalizationGroup.
8. [ ] Return iterator.

The %FinalizationGroupCleanupIteratorPrototype% Object
https://tc39.github.io/proposal-weakrefs/#sec-%finalizationgroupcleanupiterator%-object

- [ ] is an ordinary object.
- [ ] has a [[Prototype]] internal slot whose value is the intrinsic object %IteratorPrototype%.

%FinalizationGroupCleanupIteratorPrototype%.next ( )
https://tc39.github.io/proposal-weakrefs/#sec-%finalizationgroupcleanupiterator%.next

1. Let iterator be the this value.
2. [ ] If Type(iterator) is not Object, throw a TypeError exception.
3. [ ] If iterator does not have a [[FinalizationGroup]] internal slot, throw a TypeError exception.
4. Let finalizationGroup be iterator.[[FinalizationGroup]].
5. If finalizationGroup is undefined, then
  a. [ ] Return CreateIterResultObject(undefined, true).
6. Assert: finalizationGroup has [[Cells]] and [[IsFinalizationGroupCleanupJobActive]] internal slot.
7. [ ] If finalizationGroup.[[IsFinalizationGroupCleanupJobActive]] is false, throw a TypeError exception.
8. If finalizationGroup.[[Cells]] contains a Record cell such that cell.[[Target]] is empty,
  a. Choose any such cell.
  b. Remove cell from finalizationGroup.[[Cells]].
  c. [ ] Return CreateIterResultObject(cell.[[Holdings]], false).
9. [ ] Otherwise, return CreateIterResultObject(undefined, true).

%FinalizationGroupCleanupIteratorPrototype% [ @@toStringTag ]
https://tc39.github.io/proposal-weakrefs/#sec-%finalizationgroupcleanupiteratorprototype%-@@tostringtag

- [ ] The initial value of the @@toStringTag property is the String value "FinalizationGroup Cleanup Iterator".
- [ ] This property has the attributes { [[Writable]]: false, [[Enumerable]]: false, [[Configurable]]: true }.