typescript-best-practices

Type safety in TypeScript improves through enforcing best-practice patterns: use type imports for clarity and build performance, implement type guards for input validation, apply discriminated unions for exhaustive handling, and maintain explicit typing throughout. These patterns catch errors at compile time and reduce runtime defects.

Type imports use `import type` syntax to import only TypeScript types, never runtime values. Regular imports include both types and values. Type imports improve build performance by allowing the compiler to eliminate unused type-only imports and clarify intent in your code.

Secure error handling combines type guards for input validation, early returns to exit fast on invalid data, and parameterized queries to prevent injection attacks. Never expose sensitive data in error messages; validate all external input before processing and use TypeScript's type system to enforce safety constraints.

Discriminated unions organize related types with a shared literal field, enabling the compiler to narrow types safely. Exhaustiveness checking via `never` ensures all union cases are handled. Use these when modeling domain states or API responses to catch missing cases at compile time.

TypeScript best practices apply to both new projects and existing codebases. Use them during code reviews, refactoring, and security hardening. Incrementally adopt patterns like type imports and early returns; start with high-risk or frequently-modified code to maximize impact.

Best practices emphasize disciplined async patterns with Promise handling, early returns to reduce nesting, and modular composition for maintainability. These patterns simplify error propagation, improve readability, and make asynchronous code safer and easier to reason about.