Sorry! I wanted to upvote. I'm also trying to find out how the the downvote got registered.

Edit: I've found it, it's curiously related to the "which browser" discussion(!): https://news.ycombinator.com/item?id=8475210 (Posted from the Firefox this time!)

RxJS author here. I'll make sure that it's more cross platform as I do actually work for Microsoft. This has been a Netflix only training platform, but in order for us to teach more, we have to be better about supporting all browsers.