RxJS Online Test

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About the test

The RxJS online test assesses knowledge of reactive programming concepts with RxJS and the various prebuilt operators that come with the library.

The assessment includes work-sample tasks such as:

  • Using RxJS Observables to manage asynchronously created data.
  • Working with RxJS Subjects for data broadcasting.
  • Processing streams of data with Pipeable Operators.

A good RxJS developer should be able to use reactive programming and the various prebuilt operators that come with the RxJS library to create maintainable and accessible web user interfaces.

Sample public questions

7 min
Creation Operator
Pipeable Operator
RxJS Observable
RxJS Subject

Consider the following RxJS code for testing how a given damage Subject affects the health of a Player object in a game:

class Player {
  name: string;
  health: number;
  damageSubscription: Subscription;

  constructor(name, damageSubject) {
    this.name = name;
    this.health = 100;
    this.damageSubscription = damageSubject.subscribe((damage) => {
      this.health -= damage;
      console.log(this.name + " was hurt for " + damage + " damage");

  takeCover() {
        takeWhile(() => this.health < 100),
        map(() => 10),
        tap(() => console.log(this.name + " is healing, current health is " + this.health))
      .subscribe((heal) => {
        this.health += heal;
const explosion = new Subject();
const john = new Player("John", explosion);
const sam = new Player("Sam", explosion);


const paul = new Player("Paul", explosion);

What options will be true after the above code is run?

5 min
RxJS Subject

Consider the following RxJS code for pushing and logging weather data:

const weatherSubject = new _______________({temperature: 0 , rainChance: 0});
const sendWeatherData = (weatherData) => {

sendWeatherData({temperature: 35.5 , rainChance: 20});
sendWeatherData({temperature: 34 , rainChance: 25});

weatherSubject.subscribe((x) => {
  console.log("Current Temperature: " +  x.temperature);

sendWeatherData({temperature: 28 , rainChance: 50});

weatherSubject.subscribe((x) => {
  console.log("Chance of rain: " + x.rainChance);

sendWeatherData({temperature: 25 , rainChance: 90});

Fill in the blanks above so that the following output is produced after running it:

Current Temperature: 34
Current Temperature: 28
Chance of rain: 50
Current Temperature: 25
Chance of rain: 90

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4 more premium RxJS questions

Awesome Tracking, Fresh Food, Log Post Data, Dictionary Definition.

Skills and topics tested

  • RxJS
  • Bug Fixing
  • Pipeable Operator
  • RxJS Observable
  • RxJS Subject
  • Creation Operator

For job roles

  • RxJS Developer

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What others say

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Simple, straight-forward technical testing

TestDome is simple, provides a reasonable (though not extensive) battery of tests to choose from, and doesn't take the candidate an inordinate amount of time. It also simulates working pressure with the time limits.

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Product reviews

G2 - Crowd Badge
G2 - High Performer (2022)
Capterra - 4.5 Stars
Capterra - Shortlist (2023)

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