VS01670 - Web Development Engineer

JavaScript (core) - ES6+ - closures, promises, async/await, destructuring, modules, event loop, prototypes, error handling. Must understand asynchronous behaviour deeply, not just syntax

TypeScript - Typing components, props, API responses, generics, interfaces vs types. Missing from the original list - we should treat this as mandatory for all new projects

React.js - Functional components, hooks (useState, useEffect, useMemo, useCallback, useRef, custom hooks), component composition, lifting state, controlled forms, error boundaries, render performance

State management- Redux Toolkit, Zustand or Context API; plus React Query / TanStack Query for server state and caching
Node.js- Express or NestJS, middleware, routing, async patterns, streams, environment config, error handling, npm ecosystem, process management
API design- RESTful design, correct status codes, versioning, pagination, rate limiting, validation, clear error contracts

SQL & databases- PostgreSQL or MySQL - joins, indexes, transactions, normalisation, schema design, query optimisation, migrations, reading an execution plan
ORM- Prisma, TypeORM or Sequelize - plus knowing when to drop to raw SQL

HTML5 & CSS3- Semantic markup, Flexbox, Grid, responsive and mobile-first layout, cross-browser behaviour, basic accessibility (WCAG)
CSS frameworks- Tailwind CSS, Material UI, Bootstrap or styled-components
Authentication- JWT, refresh-token rotation, OAuth 2.0, session handling, role based access control, password hashing

Testing- Jest, React Testing Library; API tests with Supertest

Build tooling - Vite or Webpack, npm/yarn/pnpm, environment builds, bundlesize awareness