Fails to correctly compare objects created by constructors from another realm (like iframes)

[NickGard]

This is definitely an edge-case, but when comparing objects like Array across iframe boundaries, instanceof will not work. See MDN's example of this: https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Array/isArray#instanceof_vs_isArray

[lukeed]

Thanks, TIL but that makes sense 👍

[ljharb]

This can be fixed by avoiding instanceof or .constructor, and relying on native brand-checking mechanisms.