JavaScript Super global variable?

Question

https://code.sololearn.com/WPjGyWkmNTjI/?ref=app

With ECMA6 where does this variable stand?
Var? Obviously not let. Not constant either.

Answer 1

This is old style js syntax, where 'var' could be omitted. If you add "use strict" at the beginning, such syntax will be disabled and you get error displayed.