This is a note in reply to Kyle Simpson’s question Basics of object layout in V8 Each JavaScript object in V8 looks like this +-------+ | *---+-> hidden class (aka map) +-------+ | *---+-> out-of-object properties storage +-------+ | *---+-> elements storage +-------+ | 1 +-+ +-------+ | | 2 | | +-------+ > N slots reserved for in-object properties ~~~~~~~~~ | +-------+ | | N +-+ +-------+ There a