I'm working on application where I have desktop app and mobile app which is mostly in offline mode.
I have done for Electron based desktop app with nedb, angular2 and TypeScript. But I'm not sure that nedb can be setup with NativeScript with Ionic or not.
nedb relays on crypto module which is currently not supported by NativeScript. So basically at this very moment, you can not use nedb with a NativeScript application. More information here