Angular 2 : cannot read property 'push' of undefined

Question

In my Angular 2 application I have a function :

notification : Array<any>;
......
......
 getNotification () {
     return setTimeout(() => {
         this.AppbankService.notify(this.user.NameId)
     .subscribe(
         (response) => {
             if (response.status === 200) {
             this.notifications.push(response.json());
             console.log(typeof(this.notifications));
              }
             this.getNotification();
         }
     )
     },5000)}

In this function, I get notification from the server every 5 seconds and try to push them to an array, but a have this:

error app.module.ts:104 error : TypeError: Cannot read property 'push' of undefined(…)

Any suggestion?

Günter Zöchbauer · Accepted Answer · 2016-11-17 09:06:01Z

11

Change

notification : Array<any>;

to

notification : Array<any> = [];

answered Nov 17, 2016 at 9:06

Günter Zöchbauer

662k235 gold badges2.1k silver badges1.6k bronze badges

Sign up to request clarification or add additional context in comments.

2 Comments

Nacim Idjakirene Over a year ago

thx it works for me , but can you tell why i have to do that ? type isn't enought ?

Günter Zöchbauer Over a year ago

No, type only specifies what kind of values can be stored in this property, but it doesn't hold a value yet. With = [] we initialize it with an empty array that has the .push() method.

Arsalan Ahmed Khan · Accepted Answer · 2018-03-02 13:26:38Z

0

I had the same issue of push string message and my issue has resolved by below code.

  messages: Array<string> = [];
  add(message: string): void {
    this.messages.push(message);
}

answered Mar 2, 2018 at 13:26

Arsalan Ahmed Khan

4364 silver badges9 bronze badges

Comments

Gadhia Reema · Accepted Answer · 2018-10-05 06:06:18Z

0

I faced the same issue and then discovered that I forgot to initialize my service method itself and its type was set to any.

answered Oct 5, 2018 at 6:06

Gadhia Reema

1963 silver badges17 bronze badges

Collectives™ on Stack Overflow

Angular 2 : cannot read property 'push' of undefined

3 Answers 3

2 Comments

Comments

Comments

Your Answer

Linked

Hot Network Questions

Collectives™ on Stack Overflow

3 Answers 3

2 Comments

Comments

Comments

Your Answer

Sign up or log in

Post as a guest

Linked

Related