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TypeScript — Senior Interview Prep

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TypeScript — Senior Interview Prep

Type-level depth for a senior React/Vue + TypeScript interview. Not “what is string” — the parts that come up under “you wrote this — explain it” or “narrow this type without an as.”

Files

# Topic
01 Generics — functions, constraints, defaults, keyof/lookup
02 Conditional and mapped types (and infer)
03 Template literal types
04 Utility types reimplemented from scratch
05 Narrowing, type guards, asserts
06 The satisfies operator
07 Declaration merging and module augmentation
08 Typing React components
09 tsconfig strictness flags — what each one prevents
10 any vs unknown vs never, type vs interface, common pitfalls

How an interviewer probes TypeScript depth

  • “Type this without any” — exercises generics, conditional types, narrowing.
  • “Why is your value typed never?” — exercises distributive conditionals or empty-union narrowing.
  • “Reimplement Pick<T, K> from scratch” — exercises mapped types + keyof.
  • “What does satisfies give you that as doesn’t?” — exercises preservation of literal types and ergonomics vs assertion.
  • “Your forwardRef’d generic component lost its generic parameter — why?” — exercises React typing nuances.

Hit those, you’re senior. Stumble on them, you’re mid.

Cross-references

External resources