How to run Diagnostic checking (e.g. isLocationOn) before switching on ion-toggle in each time?

Let say the code is like below:

page.html

<ion-toggle [(ngModel)]='somethingOn' (ngModelChange)='statusChange($event)'></ion-toggle>

page.ts

import { Diagnostic } from '@ionic-native/diagnostic/ngx';

export class Page implements OnInit {

  somethingOn: boolean;

  constructor(private diagnostic: Diagnostic) {
    // should be some codes here?
  }

  ngOnInit() {
  }

  statusChange(e) {
    // or should be some codes here?
    if (this.somethingOn) {
      // ...
    } else {
      // ...
    }
  }
}

How to run Diagnostic checking (e.g. isLocationOn) before switching on ion-toggle in each time?

Thank you.