There's a babel transform for this in case you want to start using it now, before browsers support it:

https://github.com/babel/babel/tree/7.0/packages/babel-plugi...

I want to use TypeScript too, which will probably not adopt it until standardization.

We definitely want to implement it! But many parts of that specification are still in flux, so like you said, we'd like to see the proposal stabilize first to avoid problems.

Thanks for the tip! Given some of the lessons we've learned with CoffeeScript, we'll most likely wait until proposals hit at minimum stage 3 before adopting them.

I've been waiting for this for years. Even considered forking Babel... it's been a long time coming :)