What ECMAScript version does cocos2d-js support?

cocos2d-x JavaScript
#1

And also what is the version of SpiderMonkey it is using, and what version of firefox uses that same version?

I want to know what features of javascript I can and can not use in cocos. (Like for…of, Maps, arrow functions like ( )=>“asd”, etc)

#2

I manually tried modernizr in a game, and touched it a little to know exactly what javascript features cocos do and do not support.

It seems that it supports ES5 pretty well, and a lot of ES6 features. In fact it seems to support the vast majority of tests, but for the record, these are the things that you cannot do on cocos2d-js (at least on 3.9)

  • Array.prototype.values
  • WeakSet type
  • Object.assign
  • Promises in general, the property window.Promise doesn’t exist
  • String.raw
  • String.includes (can use String.contains instead which does the same)

But all the other nice stuff like Map, Set, arrow functions, optional and rest parameters, etc, works flawlessly.

PS: Also, something interesting is that firefox has a unique .watch() function for objects that also works on cocos, it is intended for debugging purposes, but it is an interesting option for making two way data binding in cocos.