There is a separate branch for ES2015+ here: https://github.com/mishoo/UglifyJS2/tree/harmony https://github.com/mishoo/UglifyJS2/tree/harmony The new primary

There is a separate branch for ES2015+ here: https://github.com/mishoo/UglifyJS2/tree/harmony https://github.com/mishoo/UglifyJS2/tree/harmony The new primary committer, alexlamsl, is good about responding to bugs & pushing out new versions fast: https://github.com/mishoo/UglifyJS2/issues?q=is%3Aissue+is%3Aopen+label%3Aharmony https://github.com/mishoo/UglifyJS2/issues?q=is%3Aissue+is%3... But there is still no CHANGELOG. He is aggressive at updating the docs, so you'll have to look at diffs yourself.