[solved] No suitable injection token for parameter 'connectionChanged' of class 'OnlineOfflineServic e'.

This error occurs when using TypeScript, possibly in Angular strict mode. 

Solution

Make sure you add your variables to your constructor before using them, like:

@Component({
    selector: 'Some',
    styleUrls: ['./Component.component.css'],
    template: ''
})
export class SomeSpecificComponent implements LatLng {
   lat:number;
   lon:number
   constructor(lat: number, lng: number){
   }
   lat(){
      return lat;
   }
   lng()
      return lon;
   }
}