I wish I could use it at work since we (Hootsuite) already use Scala heavily on the backend, but I am reluctant in part because Scala.js does not quite have financial support of Lightbend. Or so it seems, it's a bit hard to tell where Lightbend ends and the non-profit Scala Center begins. The latter did pay to get some features implemented but reading their advisory board minutes, I'm not sure if they would have enough funding to pay for the majority of Scala.js development, which if I understand correctly happens for free as part of a PhD right now (note: my information might be wrong/outdated!)
So, if anyone involved with Scala.js is reading this and has better insights on the situation, it would be nice to know.
But I will keep using it regardless. It's marvellous.