Chakra does better than most of its competition on ES6 support: <a href="http:&#x2F;&#x2F;kangax.github.io&#x2F;compat-table&#x2F;es6&#x2F;" rel="nofollow">http:&#x2F;&#x2F;kangax.github.io&#x2F;compat-table&#x2F;es6&#x2F;</a><p>(I use v8 and javascriptcore all day but I still appreciate it)