Io.js is it mandatory to use keys to run ECMA 6?

Question

Node.js

Io.js is it mandatory to use --use_strict --harmony_classes switches to run ECMA 6?

Answer 1

habrahabr.ru/post/247837
And look at the output: iojs --v8-options|grep "harmony"
and this output: iojs --v8-options | grep "in progress"
There will be keys with explanations.