Central role ble for react native. Technically a shim for the excellent noble
npm i --save react-native-ble
For ios also see the react native linking guide, but basically
npm install rnpm -g rnpm link
For android also see https://facebook.github.io/react-native/docs/native-modules-android.html#register-the-module in the paragraph starting "The package needs to be provided..." for the required edits to getPackages() in MainApplication.java.
See the noble api for usage
var noble = ('react-native-ble');
For more advanced usage, like in the eddystone_beacon_scanner, include noble directly or utilize a package that does so:
var noble = ('noble');
And follow the instructions in rn-nodeify to deep shim react-native-ble for noble.