osx-jxa should have full es6 support now, I think

[joedaniels29]

The guides could use an update, Happy to help out with it if wanted

[JMichaelTX]

Just to be clear, ES6 requires macOS Sierra 10.12+.

macOS El Capitan 10.11.6 is partially compliant with ES6. Anyone have a complete list of ES6 features supported by macOS 10.11.6?

Also of use, is this script written by @RobTrew, which will clearly identify whether or not JXA (as run in Script Editor) is ES6 compliant:

(function () {
    'use strict';

    try {
        eval('[1, 2, 3].map(x => x * 2)');
        return 'ES6';
    } catch (e) {
        return 'ES5';
    }
})();

[ELLIOTTCABLE]

Similarly, you can check ES2016 (‘ES7’) compliance pretty trivially:

(function () {
   'use strict'

   try {
      eval('2 ** 2')
      return 'ES2016'
   } catch (e) { return false }
})()

[Tatsh]

You can use the compat-table scripts, but they may require editing.