I'm looking at using a 3rd-party JS library in a plugin, but it uses ES6 - which isn't supported by the version of uglify set in package.json for M3.3 - it chokes with parse errors on the new syntax. Fortunately, there's a ES6 compatible "harmony" branch of UglifyJS, which is compatible.
Changing package.json from
...and running `npm update` fixes the parse errors, and is presumably backwards-compatible - unfortunately I can't run Behat at the moment to run check for regressions.
Would I be right in thinking that grunt-contrib-uglify will need to merge their ES6 support into their main release, before Moodle can adopt it?