Google Apps Script Javascript Standard Support [duplicate]

Question

Simple question: Can anyone point to a resource or knows anything about which standard of Javascript is supported in Google Apps Script?

I assume naturally that ES5 is fully supported, but what about ES6 (and even 7)?

Note: I mean the built-in code editor, which will appear if you open a Spreadsheet (for example), and click Tools > Script editor...

Answer 1

According to the docs Apps Script is based on JavaScript 1.6.

This table explains the correlation to the ES standards.

Answer 2

From https://developers.google.com/apps-script/guides/services/#basic_javascript_features (January 27, 2019)

Basic JavaScript features

Apps Script is based on JavaScript 1.6, plus a few features from 1.7 and 1.8. Many basic JavaScript features are thus available in addition to the built-in and advanced Google services: you can use common objects like Array, Date, RegExp, and so forth, as well as the Math and Object global objects. However, because Apps Script code runs on Google's servers (not client-side, except for HTML-service pages), browser-based features like DOM manipulation or the Window API are not available.