How to detect ECMAscript version?

Question

I want to see what ECMAscript version I\'m using in my browser(e.g,chrome 59) ,because there is some difference between ECMAscript3 and ECMAscript5 when dealing with something R

Answer 1

I don't think that's possible because browsers normally don't implement all features of an ECMAScript version at once. That's why we have libraries like Modernizr and websites like Can I use ... to find out what features can be used.

You could still build a little test that determines how RegEx in the user's browser version behaves.