the TypeScript compiler has perfect linting feedback that is designed for IDE integration, and most good IDE’s (WebStorm, Atom, Brackets, Sublime etc.) have already implemented it. It should be easy to integrate that in Cloud9 too, since the typescript npm package does all the hard work for you.
Angular 2 is written entirely in TypeScript… so this should be a prio 1 for you guys. It would make C9 so much more valuable.