React Development Standards

New Component Workflow

1. Create file — ComponentName.tsx in feature folder; co-locate ComponentName.module.scss, ComponentName.test.tsx
2. Define interface — export ComponentNameProps with TypeScript; destructure in function signature
3. Implement — functional component with hooks; use CSS Modules for styling
4. Test — RTL behavioral tests; cover render, interaction, edge cases, accessibility
5. Verify — lint + type-check + test pass; visually confirm in browser if UI

Architecture & Components (concise)

• Functional components with hooks. Follow domain/feature folder structure; co-locate tests/styles with components.
• PascalCase names; destructure props; use TypeScript interfaces for props.

interface UserCardProps { name: string; role: string }
export function UserCard({ name, role }: UserCardProps) {
  return (
    <div data-testid="user-card">
      <h3>{name}</h3>
      <span>{role}</span>
    </div>
  );
}

TypeScript

• Use interfaces for props, shared types; keep strict mode enabled in tsconfig.json. Generic constraints: <T extends Record<string, unknown>>. Discriminated unions for variant props. Avoid as casts.

Styling

• CSS Modules (.module.scss) co-located with components.
• Sass for advanced features; variables/mixins from shared libraries.
• CSS custom properties for theming.

Testing

• React Testing Library (behavior, not implementation); Jest runner.
• Co-locate tests next to components; mock external deps, API calls.
• Test accessibility, keyboard navigation; verify component public surface via unit tests.

import { render, screen } from '@testing-library/react';
import { UserCard } from './UserCard';

test('renders user info', () => {
  render(<UserCard name="Alice" role="Admin" />);
  expect(screen.getByText('Alice')).toBeInTheDocument();
  expect(screen.getByTestId('user-card')).toBeInTheDocument();
});

Verification commands + error recovery

Run these as part of your PR validation pipeline or locally:

pnpm lint        # fixable issues: pnpm lint --fix
pnpm typecheck   # run `pnpm tsc --noEmit` if alias not present
pnpm test        # rerun failing tests with `pnpm test -- -t <name>`
pnpm build       # ensure production build succeeds

If lint fails: run pnpm lint --fix; re-run. If typecheck fails: inspect reported files; add missing types. If tests fail: run with --runInBand to collect stack traces; reproduce locally.

Security

• Sanitize user-supplied HTML before rendering (e.g. dompurify); never trust client validation alone — validate server-side. See api-patterns skill for server validation patterns.