is it possible more than 3 bangles connect in one PC?

Ok - bear in mind it's as I said above - this is only for getting data from a Bangle, not the other way.

All you need to get started is Chrome's example:

https://googlechrome.github.io/samples/web-bluetooth/scan.html?namePrefix=Bangle&allAdvertisements=true

And then on the Bangle you advertise the data you want. For example:

function updateAdvertising() {
  var data = new Uint8Array(2);
  data[0] = E.getTemperature();
  data[1] = E.getBattery();
  NRF.setAdvertising({},{
    showName:false,
    manufacturer:0x0590,
    manufacturerData:data
  });
} 
updateAdvertising();
setInterval(updateAdvertising, 10000); // update every 10 seconds

Now you'll see that in Chrome, event.manufacturerData contains the data that you sent over, for every Bangle. No connection or pairing needed!

I had a quick test, and as far as I can tell it only works properly (reporting back data) in Android (not Windows or Linux). I guess Mac OS might work too, but I haven't tested