Does JavaScript garbage collection delete parent objects if sub object is still in scope?

If I have an object that contains 2 sub-objects, and I delete the pointers to the parent object and one of the child objects, but I still have a pointer to the other child object, will JavaScript delete the one child and the parent, or will the whole parent object remain even though it’s no longer addressable?

I know I could use delete to remove the other child element, but that still leaves the parent. And I want to understand GC better and whether this explicit cleanup is necessary.

var parentObj = {
    A: { subObjA: 'data' },
    B: { subObjB: 'data' }
};

var persist = parentObj.B;
parentObj = null;

After this, will the parent object and subObjA be deleted since they are no longer accessible. or will the whole object remain because I have a pointer to subObjB?