2 1998 - 3 1999 ReExp, try/catch, ...etc. 4 - - 5 2009 "strict mode", getter/setter, JSON, ...etc. 5.1 2011 - 6 (2015) 2015 class and modules, iterator, generator, arrow functions, let/const, template string, Symbol, Promise, ...etc. 2016 2016 exponentiation operator (**), Array.prototype.includes 2017 - It Works! 7