TypeScript Application Code Review Checklist

Code Structure and Organization

• Check proper use of modules and imports/exports
• Verify adherence to naming conventions (camelCase for variables/functions, PascalCase for types/classes/interfaces)
• Look for appropriate use of modern ECMAScript features
• Check appropriate separation of concerns

TypeScript-Specific Practices

• Verify strict mode is enabled in tsconfig (strict, noImplicitAny, strictNullChecks)
• Look for overuse of any; prefer unknown and precise types
• Check for unnecessary type assertions (as) and non-null assertions (!)
• Verify proper use of generics, union types, and discriminated unions
• Check for correct handling of null and undefined

Testing and Quality

• Check for comprehensive test coverage (unit, integration, end-to-end tests)
• Verify the use of appropriate testing frameworks (Jest, Vitest, Playwright)
• Look for test organization and structure
• Check for proper use of mocks, stubs, and test fixtures
• Check for consistent code style via linting and formatting (ESLint, Prettier)

Performance Considerations

• Look for unnecessary re-renders and missing memoization (frontend frameworks)
• Check for bundle size, tree-shaking, and code splitting
• Verify efficient use of async/await and Promise handling
• Look for memory leaks (uncleaned listeners, timers, subscriptions)

Dependency Management

• Verify appropriate package selection and dependency management
• Check for outdated or vulnerable packages (npm audit)
• Look for proper versioning constraints and a committed lockfile
• Check for unnecessary or duplicate dependencies

Security Issues

• Check for XSS risks (innerHTML, dangerouslySetInnerHTML, unsanitized DOM injection)
• Look for proper input validation and sanitization
• Verify authentication and authorization implementations
• Check for use of eval and other unsafe dynamic code execution
• Look for prototype pollution and unsafe deserialization
• Run npm audit for automated supply-chain security scanning
• Check that sensitive data (secrets, tokens) is not committed to code or logs

Framework-Specific Checks (React, Angular, Node.js)

• Proper component structure and state management
• Adherence to the rules of hooks and dependency arrays (React)
• Check routing, middleware, and API structure (Node.js/Express)
• Verify proper handling of server-side rendering and hydration

Documentation

• Check for comprehensive code documentation (TSDoc)
• Verify README and installation instructions
• Look for API documentation if applicable
• Check for comments explaining complex business logic