What is the best way to make the Puck log data and read it by mobile? Any ready code for that?

Yes, the /ide page uses service workers, so should actually work offline as-is. Try disconnecting from the internet and going there (obviously once you've been on it already).

The code on the Puck itself doesn't have to change. You have a few options:

• you could actually just use the nRF UART app (Adafruit's bluefruit app should do it too). If you've uploaded the getData function then just type getData(), then newline, then send - and it'll dump all the data for you
  
• You could make your own Android app using DroidScript - it's nice and easy and already has Puck.js support built in
  
• You could make your own Android/iOS app
  
• You could use service workers yourself to make your Web Bluetooth page available offline - there are a bunch of tutorials online about doing that.
  
  

Hope that helps :)