The whole implementation of the app is possible thanks to the open-source Cordova BLE plugin – cordova-plugin-ble-central
This plugin allows to scan, connect, and read/write information from a BLE device – in our case PREE device. We use this plugin to scan PREE devices, get the power of the received signal for every device, and set the Bluetooth pair connection for every attached device. Also, we used Google maps and Geolocation for storing and showing the actual location of the connected PREE device. All this stuff is required for the main feature – notify the user when you lose connection or get back to the range for some PREE device.