That requires extra bookkeeping for ordering, but it isn't really that common where people will have object literals with the same properties initialized in a d

That requires extra bookkeeping for ordering, but it isn't really that common where people will have object literals with the same properties initialized in a different order. But a much more common case is that properties added after object creating will be added in an inconsistent order, for example: o = {}; o.x = 1; o.y = 2; o.z = 3; p = {}; p.y = 4; p.x = 5; p.z = 6; When executing p.y = 4 you don't know that the object will eventually evolve to have the same properties as o.