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Angular Debounced Search with Fake API (RxJS)

By FrontendAtlas Team · Updated Jan 30, 2026

Implement an Angular debounced search using RxJS. Use debounceTime + distinctUntilChanged + switchMap to cancel stale requests, and model loading, error, and empty states so the UI feels like a real search box. This checks reactive streams, cancellation, and UI state coordination. Angular focus: debounce…

Use a standalone Angular component as the root component.
Render a search input where the user can type a query.

What you’ll build / What this tests

This premium angular coding focuses on Angular Debounced Search with Fake API (RxJS). You’ll apply angular and rxjs thinking with hard level constraints. The prompt emphasizes Implement an Angular debounced search using RxJS. Use debounceTime + distinctUntilChanged + switchMap to cancel stale….

Learning goals

Translate the prompt into a clear angular API signature and return shape.
Apply angular, rxjs, http techniques to implement angular debounced search with fake api (rxjs).
Handle hard edge cases without sacrificing readability.
Reason about time/space complexity and trade-offs in angular.

Key decisions to discuss

Define the exact input/output contract before coding.
Decide on concurrency and error propagation behavior.
Prioritize predictable edge-case handling over micro-optimizations.

Evaluation rubric

Correctness: covers required behaviors and edge cases.
Clarity: readable structure and predictable control flow.
Complexity: avoids unnecessary work for large inputs.
API discipline: no mutation of inputs; returns expected shape.
Testability: solution is easy to unit test.

Constraints / Requirements

Use a standalone Angular component as the root component.
Render a search input where the user can type a query.
Do NOT call the fake API on every keystroke; debounce input so the search runs 500ms after the…
Perform a fake async search call (e.g. in-memory array) that returns results based on the query text.
Show a loading state while the debounced search request is in flight.
Show an error state when the fake API fails.
Show a list of matching results when the request succeeds.
When the query is cleared, cancel the pending search and clear the results.
Typing quickly in the input does not trigger multiple API calls; only the final value after the user…
While a search is running, a small loading label (e.g. "Searching…") is visible.

Mini snippet (usage only)

// Example usage
const input = /* angular debounced search with fake api (rxjs) input */;
const result = solve(input);
console.log(result);

// Edge case check
const empty = input ?? null;
const fallback = solve(input);
console.log(fallback);

// Expected: describe output shape, not the implementation
// (no solution code in preview)

Common pitfalls

Mutating inputs instead of returning a new value.
Skipping edge cases like empty input, duplicates, or nulls.
Overlooking time complexity for large inputs.