Introduction to Node.js
TABLE OF CONTENTS
When Node.js needs to perform an I/O operation, like reading from the network, accessing a database or the filesystem, instead of blocking the thread and wasting CPU cycles waiting, Node.js will resume the operations when the response comes back.
This allows Node.js to handle thousands of concurrent connections with a single server without introducing the burden of managing thread concurrency, which could be a significant source of bugs.
In Node.js the new ECMAScript standards can be used without problems, as you don't have to wait for all your users to update their browsers - you are in charge of deciding which ECMAScript version to use by changing the Node.js version, and you can also enable specific experimental features by running Node.js with flags.
npm with its simple structure helped the ecosystem of node.js proliferate, and now the npm registry hosts almost 500,000 open source packages you can freely use.
The most common example Hello World of Node.js is a web server:
This code first includes the Node.js
Node.js has a fantastic standard library, including first-class support for networking.
createServer() method of
http creates a new HTTP server and returns it.
The server is set to listen on the specified port and hostname. When the server is ready, the callback function is called, in this case informing us that the server is running.
Those 2 objects are essential to handle the HTTP call.
The first provides the request details. In this simple example, this is not used, but you could access the request headers and request data.
The second is used to return data to the caller.
In this case with
res.statusCode = 200
we set the statusCode property to 200, to indicate a successful response.
We set the Content-Type header:
and we end close the response, adding the content as an argument to
Node.js is a low-level platform, and to make things easier and more interesting for developers thousands of libraries were built upon Node.js.
Many of those established over time as popular options. Here is a non-comprehensive list of the ones worth learning:
- AdonisJs, a full-stack framework highly focused on developer ergonomics, stability and confidence. Adonis is one of the fastest Node.js web frameworks.
- Express, one of the most simple yet powerful ways to create a web server. Its minimalist approach, unopinionated, focused on the core features of a server, is key to its success.
- Fastify, a web framework highly focused on providing the best developer experience with the least overhead and a powerful plugin architecture. Fastify is one of the fastest Node.js web frameworks.
- hapi, A rich framework for building applications and services that enables developers to focus on writing reusable application logic instead of spending time building infrastructure.
- koa, built by the same team behind Express, aims to be even simpler and smaller, building on top of years of knowledge. The new project born out of the need to create incompatible changes without disrupting the existing community.
- Micro, a very lightweight server to create asynchronous HTTP microservices.
- NestJS, a TypeScript based progressive Node.js framework for building enterprise-grade efficient, reliable and scalable server-side applications.
- Next.js, a framework to render server-side rendered React applications.
- Nx, power-ups to the Angular CLI which allows building full-stack applications using NestJS, Express, and Angular and easily share code between backends and frontends.
- Socket.io, a real-time communication engine to build network applications.