typescript-advanced-compiler-config

TypeScript Compiler Configuration

The tsconfig.json options that decide what the compiler catches and how fast it catches it.

Mindset

Keep strict: true as the non-negotiable baseline and treat every additional strictness flag (noUncheckedIndexedAccess, exactOptionalPropertyTypes, noImplicitReturns) as a default-on decision, not an opt-in one — the cost of a flag is some extra narrowing at the call sites it affects, and the cost of not having it is a defect the compiler could have caught but didn't. Never disable a strict-mode finding with @ts-ignore or strict: false; the defect it surfaced is still there, you've only removed the compiler's ability to tell you about it. When type-checking is slow, profile before guessing — tsc --extendedDiagnostics and project references usually explain the slowdown faster than trimming include patterns at random.

When to Apply

Use this skill when:

• Bootstrapping a tsconfig.json for a new project
• Deciding which strictness flags to enable beyond the strict bundle
• Debugging a module-resolution error (Cannot find module, wrong resolution strategy for ESM/bundler setups)
• Diagnosing and fixing slow tsc --noEmit runs

Use When

• "What should my tsconfig.json look like for a new Node/ESM project?"
• "Which strictness flags should I turn on beyond strict: true?"
• "Why is TypeScript not resolving this module the way I expect?"
• "Why is type-checking so slow, and how do I speed it up?"

Scope

In Scope

• tsconfig.json structure and common option choices.
• Strict-mode flags and what each one catches.
• Module resolution strategies (node, bundler, node16/nodenext) and their trade-offs.
• Diagnosing and improving type-checking performance.

Out of Scope

• Type-system design (generics, conditional types, unions) — see the sibling typescript-type-system skill.
• Runtime validation and type guards — see the sibling typescript-type-guards and typescript-practices skills.
• Build-pipeline or bundler configuration unrelated to the TypeScript compiler itself.