Understanding Node.js: Runtime, APIs, and Backend Frameworks

Node refers to the JavaScript runtime environment that executes code outside the browser, while NodeJS denotes the JavaScript code running within that environment.

Many developers know Node but still struggle to build backend projects because they are unfamiliar with Node APIs, lack knowledge of backend development logic, and do not know how to use Node frameworks.

In the browser we learn BOM and DOM , which are browser‑specific. Node provides its own set of APIs, and mastering them is essential for backend work.

Backend logic differs from front‑end state management: servers use session mechanisms, database operations, transaction handling, and concurrency control instead of global state stores like Vuex or Redux.

Building a backend with only native Node APIs (e.g., path模块、http模块 ) is possible but cumbersome; using a framework greatly simplifies development.

The most popular Node frameworks include:

Express.js – minimal, flexible, strong routing, large community.

Koa.js – async/await‑friendly, lightweight, modular.

NestJS – TypeScript‑first, modular, supports microservices and GraphQL.

Fastify – high performance, JSON‑Schema validation, plugin system.

Hapi.js – configuration‑centric, extensive plugins, strong security.