RxJS Online Test
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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
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() {
this.damageSubscription.unsubscribe();
interval(1000)
.pipe(
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);
explosion.next(10);
john.takeCover();
explosion.next(20);
const paul = new Player("Paul", explosion);
sam.takeCover();
explosion.next(20);
paul.takeCover();
What options will be true after the above code is run?
An online streaming platform uses the following RxJS code to log the number of seconds passed in a video:
const seconds = interval(1000).pipe(
map((x) => x + 1),
startWith(0)
);
const logger = seconds.subscribe((x) =>
console.log(`Seconds passed: ${x}`)
);
setTimeout(() => {
logger.unsubscribe();
}, 5000);
What options will be true about seconds and logger after the code above is executed?
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Skills and topics tested
- RxJS
- Bug Fixing
- Pipeable Operator
- RxJS Observable
- RxJS Subject
- Creation Operator
For job roles
- RxJS Developer
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