On the topic of adding a new meta object protocol hook for isArray, even if this was added it would likely need to have an invariant that it would always match the result of the target value. Similar to existing hooks like: handler.isExtensible() - JavaScript | MDN
This would prevent it being possible to create a value that could do odd things such as return true or false at random for Array.isArray
please tell me something I haven't published already ... the point is that at its core there's no trap ... if there was, it doesn't matter who patched what, the native Array.isArray(proxy) will produce what the native Proxy trap returns ... avoid all that and good luck with the code, but that's not interesting to me, me being forced by this thread to monkey-patch Array.isArray is the concern ... but it works like a charm, so I've moved forward weeks ago with zero regrets.
About isExtensible() I am afraid I have no interest in discussing off topic issues here, thanks for not diverging from what's being discussed in here: Array.isArray missing trap, which is not a trap that already exist neither.
to whom it might concern, or simply end up in here due similar issues, there's more to this story as ownKeys is also affected by proxy drilling down its value Proxy drilling once again ...