angular-manual-unsubscribe.ts

import { Component } from '@angular/core';
import { Subscription, interval } from 'rxjs';

@Component({
    template: `<div>{{ count }}</div>`
})
export class CounterComponent implements OnDestroy, OnInit {

    count: number;
    
    private _countSubscription: Subscription;
    
    ngOnInit() {
        this._countSubscription = interval(1000)
            .subscribe(count => this.count = count);
    }
    
    ngOnDestroy() {
        if (this._countSubscription != null) {
            this._countSubscription.unsubscribe();
        }
    }

}