HtmlUnit uses a slightly modified version of the latest code of the Rhino (https://github.com/mozilla/rhino) js engine. During the years we also provide many fixes and improvements to the project (https://github.com/mozilla/rhino/commits/master/?author=rbri). Adding support for more modern js syntax is really hard, because Rhino tries to be backward compatible (for good reasons) (eg. mozilla/rhino#1431).

Therefore i like to try to switch to another javascript engine.

This will require time and effort - you can support this via

Will use this issue to inform about the progress.