First, up front -- I am an experienced language developer and a programmer. So I know about memory management and garbage collection. I've seen lots of different kinds of heaps. And I implemented the garbage collector in Frontier, a runtime environment that has been in use constantly since 1992.
4. Then each of the levels leading to the document. So you can have values that are local to a given year, month or day, or to a specific post. (These are less common, but you do end up using these too.)
A value at a higher level in the stack overrides a value with same name at a lower level. So I may have set the default background color for all my blogs as whitesmoke, but want it to be yellow for one document.
I don't care if it's reclaimed now or at some time in the future, what I care about is that it is logically empty. When I go look for something in that array, after emptying it, I can be guaranteed that I won't find it.
I've been reading whatever I can find on the subject and the answer I see most is basically "Dear programmer you have nothing to worry about, just forget about reclaiming your structure, as soon as there are no pointers to it, the JS runtime will do it for you."
I asked Brendan Eich what he thought: "Setting the global to null should work but it is too easy via closure over-capture to leak. Search for JS leak detector devtools."