title: How to detect ECMAscript version?
body: <p>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 RegExp stuff.<br>
  I've found the relevant information about this,but I can't find a specific answer about how to detect the ECMAscript version.<br>
  Thank's in advanced.   </p>