Easy to find out. Take a look at this screenshot:

https://neomjs.github.io/pages/resources/images/helix_vdom.png

You can see components living inside the application worker using JSON based virtual dom. This is the real ES8+ code without any builds or transpilations.

The neo.mjs project is very disruptive and maybe too far ahead of its time, but it definitely works well in todays browsers.

Best regards, Tobias