Ionic2 - Global Var

app.ts

@App({
  providers: [GlobalService], // constructed once
  config: {}
})
class MyApp {
}

global_service.ts

import {Injectable} from 'angular2/core';
import {Http, Headers} from 'angular2/http';

@Injectable()
export class GlobalService {
  constructor(private http: Http) {
  }
}

page.ts

@Page({
})
export class SpecialsPage {
  // shared instance being injected
  constructor(private global: GlobalService) {
  }
}