But you are don't use NodeJS. Under the hood you are using Rhino (really slower than NodeJS). "If you have just a small project" - I think AEM for large projects. For small projects possible to use small CMS(drupal, wordpress).I agree - JS can be on the server side. But Its effects must be limited

I know how it's works :-). I mean backend JS controllers.(data-sly-use="myC.js")Expand full API for JS developers - I think it isn't a good practice. My opinion: Professional devs will write on Java(faster and flexible), JS necessary for preparing data before rendering (for low-level devs).

As I understand JS code drived by Mozilla Rhino => JS code has full access to all services(example: java.lang.System.exit).I can create a new page (example: /blabla/i-am-hidden-url) and write simple JS controller: java.lang.System.exit(0); (yesss. it work)  If I make request to:  /blabla/i-am-hidden...