best-practice-ts

This skill is the TypeScript layer. It assumes best-practice-js is already applied underneath — every rule about const/let, destructuring, arrow functions, module syntax, control flow, naming, and so on still holds. This document does not restate those rules. It only covers what changes, or gets added, once a file has a type system: tsconfig.json, the type system itself (unions, generics, narrowing, mapped/conditional types), declaration files, and the runtime-validation boundary that TypeScript cannot enforce for you.

Target: TypeScript 5.4+. All examples assume strict: true and the tsconfig.json baselines in Chapter 1. All code honors the user's Prettier config: no semicolons at statement end, single quotes, 2-space indent, no trailing commas, parenthesized single arrow params, double quotes only in JSX attributes. Semicolons do appear between members inside interface/type object bodies — Prettier leaves those alone.

When to use