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TypeScript Fundamentals Practice (Interactive)

Intuition

Learning through practice: Practice problems are like training drills — they help you apply knowledge and identify areas that need more study.

Why it matters: Regular practice builds confidence and reveals patterns in how concepts are tested. Each problem reinforces key programming concepts.

The key insight: Making mistakes during practice is valuable — each error points to a concept that needs clarification.

TypeScript — Fundamentals Practice

10 auto-graded practice problems covering TypeScript fundamentals. Select an answer, submit, and review the explanation.

Type System

Generics

Advanced Patterns

Enums and Union Types

Classes

Tooling

React Integration

Cross-References

Common Mistakes

Using any instead of unknown for dynamic data: Using any disables type checking entirely, letting runtime errors slip through. Use unknown and narrow with type guards to maintain type safety.

Ignoring exhaustiveness checking in discriminated unions: Omitting a never default case in switch statements means new union members won’t trigger compile errors. Always add a never assertion to catch missing cases.

Forgetting that Readonly is shallow: Readonly<T> only makes top-level properties readonly. Nested objects remain mutable. Use ReadonlyDeep from type-fest for deep immutability.