- add "es6": "true" in our extension.json somewhere - https://www.mediawiki.org/wiki/ResourceLoader/ES6#Example_ES6_module_in_an_extension_or_skin
- see if we need to update .eslintrc.json
ES6 allows more powerful and more modern syntax:
Can't use anything newer than ES6 yet (ES2016, etc.), but this is a good start. Will make development easier.
Refactoring ideas moved to T325348: PageTriage: Javascript refactoring to take advantage of ES6