Question 1

How do you structure types in a large TS monorepo?

Accepted Answer

Shared packages for domain types, app-local UI types, avoid circular type imports. Generate API types from OpenAPI. Keep runtime validators next to types.

Question 2

DTO vs domain model typing?

Accepted Answer

Separate transport shapes from rich domain types; map at boundaries. Prevents leaking persistence/API details into core logic.

Question 3

Dependency injection typing approaches?

Accepted Answer

Constructor typing, tokens with interfaces, frameworks (Nest) with decorators. Prefer interface-based ports for testability. Avoid concrete-only graphs.

Question 4

How do path aliases affect architecture?

Accepted Answer

Clean imports but can hide circular deps; configure consistently in TS + bundler. Prefer package boundaries over deep alias spaghetti.

Question 5

Public API surface for a TS library?

Accepted Answer

Export minimal types/functions; use package.json exports; avoid leaking internals. Version types carefully — they are breaking changes too.

Question 6

Error typing strategies?

Accepted Answer

Result types, neverthrow, typed error subclasses, or unknown + narrow at edges. Avoid throwing any. Document error contracts across services.

Question 7

Lead: set TypeScript engineering standards for a team.

Accepted Answer

strict defaults, eslint rules, type-test CI, boundary validation policy, review guidelines for any/assertions. Teach via examples. Measure any count over time. Align tsconfig across packages.

Architecture TypeScript Interview Questions

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