A lot of the problems described in this (very detailed, nice work!) comparison are not really problems so much as design decisions. Having a clone operation tha

A lot of the problems described in this (very detailed, nice work!) comparison are not really problems so much as design decisions. Having a clone operation that copies non-enumerable properties is, depending on what you're doing, a bad thing. They're not enumerable for a reason. Similarly, cloning things like getters means you're potentially copying over closures, which means your new cloned object now has references to its source and interacting with it may mutate the source. This is a pretty serious hazard that (IMO) justifies not cloning getters/setters, at least by default. Cloning freeze/seal status would also lower the usability of your cloning API, because now if you wanted to make a non-frozen copy of a frozen object, you can't use the clone API.