- ES3 / ECMAScript 3 is fully supported in all browsers.
- ES5 / ECMAScript 5 is fully supported in all modern browsers.*
- ES6 / ECMAScript 6 (ES2015) is partially supported in all modern browsers.
- ES7 / ECMAScript 7 is poorly supported in all browsers.
* = “modern browser” (IMO) refers to webkit-based browsers (Chrome and Safari) and newer versions of IE and Firefox.