lodash_groupby_style.md

A bit easier to read:

var installed = WindowController.getInstalledPlugins();
return {
  installedPlugins: _.intersection(conf.SUPPORTED_EDITORS, installed),
  uninstalledPlugins: _.difference(conf.SUPPORTED_EDITORS, installed),
}

Slightly (negligibly) more efficient:

return _.groupBy(conf.SUPPORTED_EDITORS,
  (e) => _.includes(WindowController.getInstalledPlugins(), e) ? 'installedPlugins' : 'uninstalledPlugins');

I'd probably prefer the former, but wanted to see what it would look like to only iterate through conf.SUPPORTED_EDITORS once.

I rather like the latter, but the former is probably more readable.

Like the readability of the first one.

I haven't tried them, but I just noticed ES2015 has Sets.