BehaviorSubject as simple store in Angular - Interactive Code Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the code to create a BehaviorSubject with initial value 0.

Angular

import { BehaviorSubject } from 'rxjs';

const count$ = new BehaviorSubject([1]);

Drag options to blanks, or click blank then click option'

A0

Bnull

Cundefined

D''

Attempts:

3 left

💡 Hint

Common Mistakes

Using null or undefined as initial value causes errors.

Leaving the initial value empty.

The BehaviorSubject needs an initial value. Here, 0 is the starting number.

2fill in blank

medium

Complete the code to subscribe and log the current value from the BehaviorSubject.

Angular

count$.[1](value => console.log(value));

Drag options to blanks, or click blank then click option'

Aemit

Bsubscribe

Clisten

Dobserve

Attempts:

3 left

💡 Hint

Common Mistakes

Using non-existent methods like emit or listen.

Trying to access value directly without subscribing.

To get updates from a BehaviorSubject, use subscribe.

3fill in blank

hard

Fix the error in updating the BehaviorSubject's value.

Angular

count$.[1](count$.value + 1);

Drag options to blanks, or click blank then click option'

Aset

Bchange

Cupdate

Dnext

Attempts:

3 left

💡 Hint

Common Mistakes

Using set or update which do not exist on BehaviorSubject.

Trying to assign value directly.

To update a BehaviorSubject's value, use the next method.

4fill in blank

hard

Fill both blanks to create a simple store with BehaviorSubject and expose it as an observable.

Angular

private countSubject = new BehaviorSubject([1]);

public count$ = this.countSubject.[2]();

Drag options to blanks, or click blank then click option'

A0

BasObservable

Csubscribe

Dnext

Attempts:

3 left

💡 Hint

Common Mistakes

Exposing the BehaviorSubject directly instead of asObservable.

Using subscribe instead of asObservable.

The store starts with 0 and exposes the observable using asObservable() to prevent external updates.

5fill in blank

hard

Fill all three blanks to implement an increment method that updates the BehaviorSubject's value.

Angular

increment() {
  const current = this.countSubject.[1];
  this.countSubject.[2](current [3] 1);
}

Drag options to blanks, or click blank then click option'

Avalue

Bnext

C+

Dsubscribe

Attempts:

3 left

💡 Hint

Common Mistakes

Trying to subscribe inside increment method.

Using wrong operators or methods to update value.

Get the current value with value, then call next with current plus one.