Phantom does not support more recent JS syntax/tweaks. We have an app that is aimed at more recent browsers only so can use latest ES6 features, and had to move

Phantom does not support more recent JS syntax/tweaks. We have an app that is aimed at more recent browsers only so can use latest ES6 features, and had to move from Phantom to in-browser tests (the alternative would be to use babel for transpilation, but then we wouldn't be testing the code that is actually released to users)