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LetsGit.IT/Categories/TypeScript
TypeScriptmedium

What is the never type and when is it used?

Tags
#types#never
Back to categoryPractice quiz

Answer

never represents values that never occur, such as functions that throw or never return (infinite loops).

Advanced answer

Deep dive

Expanding on the short answer — what usually matters in practice:

  • Context (tags): types, never
  • Explain the "why", not just the "what" (intuition + consequences).
  • Trade-offs: what you gain/lose (time, memory, complexity, risk).
  • Edge cases: empty inputs, large inputs, invalid inputs, concurrency.

Examples

A tiny example (an explanation template):

// Example: discuss trade-offs for "what-is-the-never-type-and-when-is-it-used?"
function explain() {
  // Start from the core idea:
  // never represents values that never occur, such as functions that throw or never return (in
}

Common pitfalls

  • Too generic: no concrete trade-offs or examples.
  • Mixing average-case and worst-case (e.g., complexity).
  • Ignoring constraints: memory, concurrency, network/disk costs.

Interview follow-ups

  • When would you choose an alternative and why?
  • What production issues show up and how do you diagnose them?
  • How would you test edge cases?

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