How do I declare a arrray in Ionic and use?

Question

export class StarterorderPage implements OnInit {
  $orders: [
    { id: number, description: string }
  ];
  constructor( public http: HttpClient, private route: ActivatedRoute) { }

  ngOnInit() {
  }

  MyFunction() {
    this.$orders[0].id = 230;
    this.$orders[0].description = 'descricao numero duzentos e trinta ';
    console.log('Observe->', this.$orders[0].id, this.$orders[0].description);
  }

ERROR Typeerror: Cannot read Property '0' of Undefined At Starterorderpage.push.. /src/app/starterorder/starterorder.page.ts.StarterorderPage.Apistarterorder (starterorder.page.ts:24) At object.Eval [as handleEvent] (Starterorderpage.html:24) handleEvent (core.js:23107) at callWithDebugContext (core.js:24177) At object.debugHandleEvent [as handleEvent] (core.js:23904) dispatchEvent (core.js:20556) at core.js:21003 At Htmlbuttonelement. (Platform-browser.js:993) At Zonedelegate.push.. /node_modules/zone.js/dist/zone.js.Zonedelegate.invokeTask (zone.js:423) At Object.onInvokeTask (core.js:17290)

This code is not working!!! How I can declare and add values and then use them?

Answer 1

To add elements to an array, do so:

MyFunction() {
    this.$orders.push({id: 230, description: 'descricao numero duzentos e trinta '});
    console.log('Observe->', this.$orders[0].id, this.$orders[0].description);
}

I always like to start an even empty array. This avoids many problems:

    $orders: { id: number, description: string }[] = [];