The Closure Compiler supports compiling ES6 code already, and can also do transpilation down to ES3/ES5. [1][2] Google also has the Traceur Compiler which does

The Closure Compiler supports compiling ES6 code already, and can also do transpilation down to ES3/ES5. [1][2] Google also has the Traceur Compiler which does transpilation of new JS features (ES6, ES7 proposals, and a couple of features that aren't in either) into older versions. [3] [1]: https://github.com/google/closure-compiler/wiki/Releases#october-15-2015-v20151015 https://github.com/google/closure-compiler/wiki/Releases#oct... [2]: https://github.com/google/closure-compiler/wiki/ECMAScript6#transpilation https://github.com/google/closure-compiler/wiki/ECMAScript6#... (might be a bit out of date, since there have been releases since that document was last edited) [3]: https://github.com/google/traceur-compiler https://github.com/google/traceur-compiler