filter elements from array core interview pattern Pattern
Pattern hubs are for building transferable solving frames. Learn the recognition signals first, then drill state definition, update rules, and edge explanation until the pattern feels stable.
Pattern brief
Recognize first
Tests knowledge of JavaScript's `filter()` method and custom function behavior.
Solve rhythm
State the active state and invariant first, explain how each update preserves them, then pressure-test with counterexamples.
Most common miss
Not handling edge cases like an empty array or invalid return values from the filtering function.
Recognition signals
- Tests knowledge of JavaScript's `filter()` method and custom function behavior.
- Checks understanding of handling edge cases like empty arrays or non-truthy values.
Solve flow
- 1. Define the active state/window.
- 2. Update state while preserving invariants.
- 3. Validate with edge-heavy examples.
Common misses
- Not handling edge cases like an empty array or invalid return values from the filtering function.
Recommended Ladder
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