Mandy uses ES6 and new shit that is only supported in the "latest" browsers (firefox >= 52, ...).
There should be some warning displayed to notify users their browser is too old.
It should be possible to transpile the es6 code to es5 so that everyone could access Mandy out of the box. I think that is the way es6 is usually handled. I suggest to use webpack and babel to do that.
Mandy uses ES6 and new shit that is only supported in the "latest" browsers (firefox >= 52, ...). There should be some warning displayed to notify users their browser is too old.