TypeScript Writing Code

Quick reference for writing production-quality TypeScript code. Each section summarizes the key rules — reference files provide full examples and edge cases.

Strict TypeScript Configuration

This project enforces maximum type safety through tsconfig.base.json. Zero any tolerance — no exceptions.

Key Flags

• strict: true — Enables all strict type-checking options as a group.
• noImplicitAny: true — Every value must have an explicit or inferable type. No implicit any.
• strictNullChecks: true — null and undefined are distinct types. Must be handled explicitly.
• noUncheckedIndexedAccess: true — Array/object index access returns T | undefined. Always check before using.
• noUnusedLocals: true — Unused variables are compile errors, not warnings.
• noUnusedParameters: true — Unused function parameters are compile errors.
• noImplicitReturns: true — Every code path in a function must return a value.
• isolatedModules: true — Required for Vite/esbuild compatibility. Prevents features that need full-program analysis.