typescript-expert-2025

Configure tsconfig by setting strict mode, module resolution, and target runtime. Modern projects typically enable strict, use ESM or CommonJS based on your environment (Bun, Node 22+, or Deno), and adjust lib and target settings. This ensures type safety and compatibility with your chosen runtime.

Choose your runtime (Bun, Node 22+, or Deno), initialize package.json, configure tsconfig for that environment, select a linter (ESLint with TypeScript support), and scaffold your project structure. Each runtime has different module and bundling defaults, so align your tsconfig and tooling choices accordingly.

Use satisfies to validate a value against a type without changing its inferred type, and as const to narrow literal types and prevent inference widening. These patterns improve type safety in real-world architectures—satisfies catches mismatches early, and as const ensures precise type narrowing for constants and configurations.

Linting for TypeScript requires ESLint with typescript-eslint parser and plugins to catch type-related issues and enforce best practices. Pair it with a formatter like Prettier and configure rules aligned with your project's strictness level and coding standards.

Configure tsconfig to output both module formats, use conditional exports in package.json to direct ESM and CommonJS consumers to the correct entry points, and ensure your build process generates both versions. This lets downstream projects choose their preferred import style.

Template literal types combine literal strings with union types to generate precise string types. Use them to model constrained string patterns, enforce naming conventions, or derive types from string patterns—they're powerful for type-safe APIs and configuration objects.