@Darius
although I do most of my programming in js and managed to create some very complex programs, your code looks way prettier and cleaner than mine! :-D

So I have good news and bad news:
I’ve managed to pair to the mooshimeter in your app, but I get an exception:
index.html:1 Uncaught (in promise) DOMException: Unsupported device.

The way I did achieve that was this:
1. enable experimental features in nw.js by adding this line in package.json.
"chromium-args": "--enable-experimental-web-platform-features"
2. start the app
3. open windows-settings, under bluetooth you will find the mooshimeter (not paired)
4. click on connect in the app, it should show a dialog indicating that it is searching for devices
5. click on pairing in windows settings – use code “0000” then it should pair
6. in the app dialog the mooshimeter should appear
7. open chrome-dev-tools by hitting F12
8. hit “pair” on the app dialog – the dialog closes and you can see the “unsupported device” message in dev-tools console