combineLatest and forkJoin for combining in Angular - Interactive Code Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the code to import the operator that emits the latest values from multiple observables.

Angular

import { [1] } from 'rxjs';

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

AcombineLatest

BforkJoin

Cmap

Dfilter

Attempts:

3 left

💡 Hint

Common Mistakes

Choosing forkJoin instead of combineLatest

Importing unrelated operators like map or filter

The combineLatest operator emits the latest values from multiple observables whenever any of them emit.

2fill in blank

medium

Complete the code to import the operator that waits for all observables to complete and then emits their last values.

Angular

import { [1] } from 'rxjs';

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

AforkJoin

BcombineLatest

Cmerge

Dconcat

Attempts:

3 left

💡 Hint

Common Mistakes

Choosing combineLatest instead of forkJoin

Confusing merge or concat with forkJoin

The forkJoin operator waits for all observables to complete and then emits their last emitted values as an array.

3fill in blank

hard

Fix the error in the code by completing the operator used to combine observables that emits only when all complete.

Angular

forkJoin([obs1, obs2]).subscribe(values => {
  console.log(values);
});

// The operator used is [1]

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

AcombineLatest

Bconcat

CforkJoin

Dmerge

Attempts:

3 left

💡 Hint

Common Mistakes

Using combineLatest instead of forkJoin

Using merge which emits values as they come

forkJoin is the correct operator to emit values only after all observables complete.

4fill in blank

hard

Fill both blanks to create a combined observable that emits the latest values from obsA and obsB.

Angular

const combined$ = [1]([obsA, obsB]);
combined$.subscribe(([valA, valB]) => {
  console.log(valA, valB);
});

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

Aconcat

BforkJoin

Cmerge

DcombineLatest

Attempts:

3 left

💡 Hint

Common Mistakes

Using forkJoin which waits for completion

Using merge which merges emissions but does not combine latest values

combineLatest combines observables and emits the latest values whenever any observable emits.

5fill in blank

hard

Fill all three blanks to create a forkJoin that waits for obsX, obsY, and obsZ to complete and then logs their last values.

Angular

forkJoin([[1], [2], [3]]).subscribe(results => {
  console.log(results);
});

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

AobsX

BobsY

CobsZ

DobsA

Attempts:

3 left

💡 Hint

Common Mistakes

Using the wrong observables or missing one

Confusing forkJoin with combineLatest here

forkJoin waits for all observables to complete and then emits their last values as an array.