Re:A one-line package broke `npm create-react-app`
by suyjuris on Saturday April 25, 2020 @06:33PM
(#22982204)
In case someone else is also confused by this, it seems that instanceof checks whether the objects prototype matches, and these prototypes are not shared across different contexts, which iframes are [0]. (Though I would still like to know why it works like this.)
[0] https://developer.mozilla.org/en-US/docs/Web/JavaScript/Refe...