coding-standards

Apply a shared baseline of conventions covering naming, immutability, error handling, and file organization, then reference it during code reviews. This Skill provides that baseline with concrete pass/fail examples for TypeScript, JavaScript, and React code.

Always use the spread operator to create updated copies of objects and arrays instead of mutating them directly. For example, use {...user, name: 'New Name'} rather than user.name = 'New Name', and [...items, newItem] rather than items.push(newItem).

Use it for cross-project concerns like naming, readability, immutability, and code smell review. For React hooks, rendering patterns, backend architecture, or API design, defer to the dedicated frontend-patterns, backend-patterns, or api-design skills.

Define a Zod schema describing the expected shape, then call schema.parse(body) inside your route handler. Catch ZodError to return a 400 response with validation details, keeping invalid data out of your business logic.

Watch for functions longer than about 50 lines, nesting deeper than a few levels, and unexplained magic numbers. Fix them by splitting functions, using early returns to flatten logic, and replacing literals with named constants.