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Valid Anagram

By FrontendAtlas Team · Updated Jan 31, 2026

Return true if two strings are anagrams (same characters with the same counts). Treat strings as case-sensitive and include all characters.

What you’ll build / What this tests

This premium javascript coding focuses on Valid Anagram. You’ll apply strings and algorithms thinking with easy level constraints. The prompt emphasizes Return true if two strings are anagrams (same characters with the same counts). Treat strings as….

Learning goals

Translate the prompt into a clear javascript API signature and return shape.
Apply strings, algorithms, sorting techniques to implement valid anagram.
Handle easy edge cases without sacrificing readability.
Reason about time/space complexity and trade-offs in javascript.

Key decisions to discuss

Define the exact input/output contract before coding.
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

Handle empty strings and mixed casing without errors.
Do not mutate inputs; return a new sorted output.
Handle empty or missing inputs without throwing errors.
Keep runtime close to linear time where possible.
Prefer a pure function: no side effects beyond the return value.

Mini snippet (usage only)

// Example usage
const s = /* valid anagram input */;
const t = /* config */;
const result = isAnagram(s, t);
console.log(result);

// Edge case check
const empty = s && t ?? null;
const fallback = isAnagram(s, t);
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.