TypeScript Configuration Mastery

tsconfig Deep Dive

• strict Mode: Enables all strict checks — strictNullChecks (null/undefined must be explicit), noImplicitAny (no untyped variables), strictFunctionTypes (function argument types checked). Always enable for new projects
• Module Resolution: moduleResolution: 'bundler' (modern, for Vite/webpack) vs 'node' (Node.js resolution). baseUrl + paths for path aliases: '@/components/*' → 'src/components/*'
• Target & Module: target: 'ES2022' (output JS version), module: 'ESNext' (module system). Target affects which features get downleveled. Module affects import/export syntax
• Project References: composite: true + references: [{path: './packages/shared'}] — TypeScript monorepo support. Incremental builds, cross-package type checking, build ordering
• Declaration Files: declaration: true generates .d.ts files — type definitions for library consumers. declarationMap: true for source navigation. emitDeclarationOnly for type-only packages
• Strict Configuration Example: strict: true, noUncheckedIndexedAccess: true (array access returns T | undefined), exactOptionalProperties: true (undefined vs missing), verbatimModuleSyntax: true (import type enforcement)