Google’s proposes “use strong”; a subset of JavaScript that will allow V8 to enjoy some significant speed boosts
Like the restrictions in Strict Mode, Strong Mode aims to boost JavaScript performance. Some of the dynamic aspects of JavaScript hold back VM speed. Instead of “use strict”; it would be “use strong”; Strong Mode is actually a subset of Strict Mode.
The changes are still in the proposal stage but could have a bright future.
Restrictions in Strong Mode include accessing missing properties throw exceptions, arrays cannot be sparse, all scoping errors are static, and classes are immutable.
Read more from The Google Developers Blog