How to unsubscribe an events subscription

Question

I am using events to subscribe an event in my ionic 3 application. It seems there are two ways to unsubscribe the subscription as given in the unsubscription1() and unsubscription2()

Could you please tell what is the difference of these two methods? are both of them can unsubscribe the subscription as expected?

import { Events } from 'ionic-angular'; ... messageSubscription: any constructor(private events: Events ...){ ... } subscription(){ messageSubscription = this.events.subscription("newmessage", () => { ... } } unsubscription1(){ this.events.unsubscription("newmessage") } unsubscription2(){ messageSubscription.unsubscribe() }

Jobelle · Accepted Answer · 2020-07-31 07:03:07Z

Declare a variable for destroy condition

public destroyed = new Subject();

Add ngDestroy lifecycle hook

ngOnDestroy() { this.destroyed.next(); this.destroyed.complete(); }

And use takeUntil(). Using an operator like takeUntil instead of manually unsubscribing will also complete the observable, triggering any completion event on the observable.

 this.events. .pipe(takeUntil(this.destroyed)) subscription("newmessage", () => { ... }

Sivakumar Tadisetti · Accepted Answer · 2020-07-31 08:00:00Z

As per the Ionic Documentation, there are no .subscription and .unsubscription methods on Events
There are only .subscribe(<eventname>, () => {}) and .unsubscribe(<eventname>, () => {})
this.events.subscribe(<event>, () => {}) return type is void.
So messageSubscription variable holds nothing and events won't get unsubscribed in the below code

unsubscription2() { messageSubscription.unsubscribe(); }

So the correct code for subscribing and unsubscribing is below

import { Events } from 'ionic-angular'; ... constructor(private events: Events...) { ... } subscription() { this.events.subscribe("newmessage", () => { ... }); } unsubscription1() { this.events.unsubscribe("newmessage") }

Collectives™ on Stack Overflow

How to unsubscribe an events subscription

2 Answers 2

Comments

Comments

Hot Network Questions

Collectives™ on Stack Overflow

2 Answers 2

Comments

Comments

Related