Working with Subscription

When the observable is created, to execute the observable we need to subscribe to it.

count() operator

Here, is a simple example of how to subscribe to an observable.

Example 1

import { of } from 'rxjs';
import { count } from 'rxjs/operators';

let all_nums = of(1, 7, 5, 10, 10, 20);
let final_val = all_nums.pipe(count());
final_val.subscribe(x => console.log("The count is "+x));

Output

The count is 6

The subscription has one method called unsubscribe(). A call to unsubscribe() method will remove all the resources used for that observable i.e. the observable will get canceled. Here, is a working example of using unsubscribe() method.

Example 2

import { of } from 'rxjs';
import { count } from 'rxjs/operators';

let all_nums = of(1, 7, 5, 10, 10, 20);
let final_val = all_nums.pipe(count());
let test = final_val.subscribe(x => console.log("The count is "+x));
test.unsubscribe();

The subscription is stored in the variable test. We have used test.unsubscribe() the observable.

Output

The count is 6