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Published on 3/6/2025
balligh-insage/claida-typescript-rules

Rules
  • Focus on type safety, clarity, and maintainability.
  • Favor functional programming techniques (pure functions, small composable utilities).
  • Use strict TypeScript (no any, minimal unknown, prefer discriminated unions over type casts).
  • Offer concise and technically accurate solutions, with short code snippets where beneficial.
  • Keep code examples minimal, well-typed, and aligned with advanced TypeScript patterns (generics, union narrowing, branding, etc.).
  • Use kebab-case for directories and files (e.g., my-utility.ts).
  • Use camelCase for variables and functions (e.g., fetchData, isValidUser).
  • Name boolean variables with verbs like is, can, has, or should.
  • Prefer interfaces for objects and types for unions or mapped types.
  • Keep each type or interface definition minimal and purposeful.
  • Use generics to enforce correctness in function or component signatures.
  • Use arrow functions for short utilities or inline callbacks.
  • For complex logic, define named functions to keep code discoverable.
  • Never use any. Use unknown if an absolutely unconstrained type is required, and then narrow it.
  • Always attempt type narrowing or discriminated unions.
  • Use JSDoc for exported functions or complex types.
  • Embrace union types (e.g. string | number) and narrow them with if (typeof val === 'string') { ... }.
  • Discriminated unions: use a literal property (like type: 'loading' | 'success' | 'error') for clear narrowing blocks.
  • For flexible data shapes, wrap them in <T> generics.
  • Constrain generics (<T extends object>) to maintain correctness.
  • Use as const for immutable data or literal inferences.
  • For advanced runtime checks, define assertion or predicate functions.
  • For advanced transformations, use extends, infer, and keyof responsibly.
  • Use template literal types for creating dynamic string types or route definitions.
  • Use Zod or similar schema libraries for runtime validation, refining to strong TS types.
  • Distinguish logically unique strings with branding/nominal types.
  • For multi-step flows or complex conditions, define discriminated unions representing each state.
  • Keep each function under ~20 lines, focusing on a single task. If it grows, refactor to smaller utilities.
  • For fetch or external calls, wrap results in typed functions or custom hooks, ensuring strict input/output shapes.
  • Detect invalid branches early with exhaustive checks.
  • Avoid unguarded type assertions (as SomeType) unless absolutely certain.
  • Keep strictNullChecks on, handle null/undefined explicitly.
  • Use ESLint + TypeScript rules to enforce consistent style, naming, no unused vars.
  • Consider Prettier for consistent formatting.
  • Test each type-level utility and data transformation with frameworks like Jest.