Angular2 - stop / cancel / clear observable in routerOnDeactivate() [duplicate] - service

Question

This question already has an answer here:
End Observable interval when route changes in Angular
(1 answer)
Closed 6 years ago.
I'm new to Angular2 so apologies if this is a trivial question. I can't seem to stop interval when I click to a different link. This component fetches data from DB table every 3,5s and it is used as a chat, so 100 users can add to it at any point. I don't want this to run in the background all the time, so I thought I'll use routeronDeactivate() function to make it stop when user is on a different link.
I think I'm doing something wrong. Can anyone help me please?
export class FeedComponent {
public feeditems: Feed[];
public timer;
constructor(private _feedService: FeedService) {
}
getArticlesJSON() {
console.log('getArticlesJSON');
this._feedService.getFeedJSON()
.subscribe(
data => this.feeditems = data,
err => console.log(err),
() => console.log('Completed')
);
}
routerOnDeactivate() {
// this.timer.remove();
// this.timer.dematerialize();
// clearInterval(this.timer);
console.log('-- deactivate ');
// console.log('-- deactivate ' + JSON.stringify(this.timer));
}
routerOnActivate() {
this.timer = Observable.timer(5000,3500);
this.timer.subscribe(() => {
this.getArticlesJSON();
});
console.log('++ activate ' + JSON.stringify(this.timer));
}
}

Answer 1

routerOnActivate() {
this.timer = Observable.timer(5000,3500);
this.subscription = this.timer.subscribe(() => {
this.getArticlesJSON();
});
}
routerOnDeactivate() {
this.subscription.unsubscribe();
}