0.1.3: The demo/index.html seems to work on all browsers but however I can’t get my manual code to work on any browser, the imports are loaded successfully but keep receiving this Uncaught Error: WeakMap expected key. I have submitted an issue to the repo.
0.2.5: My pen is working on Chrome Canary and Opera now, did a contact with the author and it seemed before 0.2.0, there used to be a problem with the ShadowDOM when trying to open paypal checkout in the same windows so what he did was to open it in the new windows in version later than 0.2.0. However, on Firefox and Safari it still does not work, did submit an issue to the author https://github.com/morbidick/paypal-express-checkout/issues/4