How can I use decorators today?

I see decorators being used today already in some javascript code. My question is really two fold.

First:

If decorators have not even been finalized how is it possible to use them in production code, today? Won’t browser support be non-existent?

Second:

Given it is possible to use it today, as some open source projects would suggest, what’s a typically recommended setup for getting decorators to work?

How can I use decorators today?