I am not sure to what your question is referring to, but FYI, JSweet follows the same pace as TypeScript in terms of JavaScript generation. So it already supports most of ES6 AFAIK.
It's all closure-based jquery plugin module format.......
If you're gonna compile to "javascript" either target a version of node that's been released in the past year or target webassembly.
Otherwise you're just another coffeescript.