Angular2 Array objects

Question

I would like to add in an array of objects, but it does not work: Can not set property '0' of undefined

I try to put in this.positions [0] = the PositionMap object

I have decreased the size of the code for better readability, but the rest works

Here is my code:

import { Component, ViewChild, ElementRef } from '@angular/core';
import { NavController } from 'ionic-angular';
import { FormBuilder, FormGroup, Validators } from '@angular/forms';
import { Geolocation } from 'ionic-native';

declare var google;

@Component({
  selector: 'page-home',
  templateUrl: 'home.html'
})
export class HomePage {

  positions: PositionMap[] = [];

  @ViewChild('map') mapElement: ElementRef;

  constructor(public navCtrl: NavController) {
    this.positions = [];
  }

ionViewDidLoad(){
    this.loadMap();
    this.autocomplete();
  }

  autocomplete() {
      autocompleteDepart.addListener('place_changed', function() {
        var place = autocompleteDepart.getPlace();
        let tmpPosition = new PositionMap(place.geometry.location.lat(), place.geometry.location.lng()); 
        this.positions[0] = (tmpPosition); 
        return;
      });
  }
}

export class PositionMap {
  latitude: number;
  longitude: number;
  constructor(_latitude: number, _longitude: number) {
     this.latitude = _latitude;
     this.longitude = _longitude;
  }
}

My table is well declared in the class and in the constructor, but yet is not known in the function.

JB Nizet · Accepted Answer · 2016-12-22 19:14:11Z

2

You're using this from a callback function. This callback function must first be bound to this. The easiest way is to use an arrow function:

autocompleteDepart.addListener('place_changed', () => {
  ...
});

answered Dec 22, 2016 at 19:14

JB Nizet

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