Hi I wrote the compiler, the reasons for JavaScript are:

- It was for my conference talk for a JavaScript audience.

- JavaScript is the language I use for 99% of my work.

- JavaScript has a much larger audience.

- I'm a maintainer of a JavaScript compiler (http://babeljs.io/) and I want more people to be able to contribute.

- JavaScript is totally fine for a compiler.

Also, hating on programming languages is dumb.