Cannot read property 'push' of undefined(…) in angular2

Question

this is the error saying " cannot read property 'push' of undefined " when using the code below

  let deal = new Deal(  5, 'afaf', 'dafa',5,23 ) 
  this.publicDeals.push( deal )   // gives a error saying Cannot read property 'push' of undefined(…)

The whole is shown below

export class Deal { 
  constructor(
    public id: number,
    public name: string,
    public  description: string,
    public originalPrice: number,
    public salePrice: number
      ) { }    
}

In another component,

import { Component, OnInit } from '@angular/core'; 
import { Deal } from '../deal';
import { DealService } from '../deal.service';

@Component({
  selector: 'public-deals',
  templateUrl: 'public-deals.component.html',
  styleUrls: ['public-deals.component.css']
})

export class PublicDealsComponent implements OnInit {
  publicDeals: Deal[];

  constructor(
    private dealService: DealService) {
  }

  ngOnInit(): void {    
      let deal = new Deal(  5, 'afaf', 'dafa',5,23 ) 
      this.publicDeals.push( deal )   // gives a error saying Cannot read property 'push' of undefined(…)

  }

  purchase(item){
    alert("You bought the: " + item.name);
  }
}

Nae · Accepted Answer · 2018-09-27 13:33:31Z

183

publicDeals is not initiated;

publicDeals: Deal[] = [];

edited Sep 27, 2018 at 13:33

Nae

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answered Oct 27, 2016 at 17:54

kit

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5 Comments

Rahal Danthanarayana Over a year ago

Worked for the Angular 7

Brandon Over a year ago

Works with Angular 9 too. Waiting for the guy who tries it with Angular 10

Naheed Shareef Over a year ago

M the one who tried with Angular 10, It's working over here, Great

Jaypal Sodha Over a year ago

It doesn't have anything to with Angular 2,3,4....Angular 12. There was a syntax error. It will work fine for every version of Angular, until and unless Angular changes its syntax for Array.

Klon Over a year ago

Ladies and gents... I can reassure you that it also works with Angular 14!

Rajesh.k · Accepted Answer · 2017-09-12 12:58:24Z

14

you have to initialize array using below:

publicDeals: Deal[] = [];

or

publicDeals: Deal[] = new Array();

answered Sep 12, 2017 at 12:58

Rajesh.k

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Comments

Nae · Accepted Answer · 2018-09-27 14:04:32Z

5

Here goes the number array:

items : number[ ] = [ ];

edited Sep 27, 2018 at 14:04

Nae

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answered Jan 11, 2018 at 15:01

Hiran Walawage

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Comments

Sathiamoorthy · Accepted Answer · 2021-07-14 13:49:16Z

2

Use the below approach for when you are adding the element into the array. the below code will work for all angular versions.

const publicDeals: Deal[] = []; //initialize the array
publicDeals.push(deal);

edited Jul 14, 2021 at 13:49

answered Jun 6, 2020 at 9:03

Sathiamoorthy

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Comments

Kaustubh Khare · Accepted Answer · 2017-11-28 11:41:21Z

1

If you use AngularFire5.0 Before pushing you must list your items

const afList = afDb.list('items');
afList.push({ name: 'item' });

you should see the update of Angularfire 5.0 here

edited Nov 28, 2017 at 11:41

Kaustubh Khare

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answered Nov 28, 2017 at 11:09

thabet

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Comments

Tomer Shetah · Accepted Answer · 2021-01-19 08:09:02Z

1

Works with

publicDeals: Deal[] = [];

I had the same issue before with the initialization

edited Jan 19, 2021 at 8:09

Tomer Shetah

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answered Jan 19, 2021 at 7:48

Kash

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Comments

Thomas Raj · Accepted Answer · 2021-06-03 02:03:13Z

1

My mistake was I wasn't declaring the array correctly. It was

optionsArray:any[];

It should be

optionsArayy:any=[];//(missing equal to)

Note: This creates an empty Array of type "any"

answered Jun 3, 2021 at 2:03

Thomas Raj

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