What is NodeJS?

Node.js is a popular JavaScript runtime that allows developers to build fast and scalable server-side applications. It uses an event-driven, non-blocking I/O model that makes it lightweight and efficient, perfect for building real-time web applications.

History of NodeJS

Node.js was created in 2009 by Ryan Dahl and has become one of the most popular and widely-used JavaScript runtime environments, especially for building web servers and networking applications. It is built on Chrome's V8 JavaScript engine, which allows it to execute JavaScript code at high speeds.

Why should we use NodeJS?

1. Fast and efficient: Node.js is built on Chrome's V8 JavaScript engine, which makes it fast and efficient for running JavaScript code.

2. Asynchronous and non-blocking: Node.js uses an event-driven, non-blocking I/O model, which makes it well-suited for real-time applications.

3. Large ecosystem of open-source libraries: Node.js has a large ecosystem of open-source libraries, known as "modules", which can be easily installed and used in your applications. These modules provide a wide range of functionality, from parsing HTTP requests to interacting with databases.

4. Easy to learn: If you are already familiar with JavaScript, then learning Node.js will be relatively easy. This makes it a great choice for developers who want to build web applications using a language they already know.

5. Great for microservices: Node.js is well-suited for building microservices, which are small, independent services that work together to build larger applications. This architecture allows for better scalability and maintainability.

How to Install NodeJS?

To get started with Node.js, you will need to have a basic understanding of JavaScript and web development concepts. You will also need to have Node.js installed on your machine. You can download the latest version of Node.js from the official website (nodejs.org).

Introduction to REPL

Once you have Node.js installed, you can start building your first Node.js application. One of the easiest ways to get started is to use the Node.js REPL (Read-Eval-Print-Loop). The REPL allows you to run JavaScript commands in the terminal and see the results immediately.

To start the REPL, simply open up your terminal and type node. You should see a prompt where you can enter JavaScript commands. For example, you can try entering 1 + 1 and pressing enter. You should see the result 2 printed in the terminal.

Creating your First NodeJS App

To create a more advanced Node.js application, you will need to use a text editor and create a .js file. The most basic Node.js application looks like this:

const http = require('http');

const hostname = '127.0.0.1';
const port = 3000;

const server = http.createServer((req, res) => {
  res.statusCode = 200;
  res.setHeader('Content-Type', 'text/plain');
  res.end('Hello World\n');
});

server.listen(port, hostname, () => {
  console.log(`Server running at http://${hostname}:${port}/`);
});

This code creates an HTTP server that listens on port 3000 and returns "Hello World" when someone visits the site. You can run this code by saving it to a file, such as app.js. Now, you can try running node app.js in the terminal. If you visit http://localhost:3000 in your web browser, you should see the message "Hello World" displayed.

Congrats! You build your first NodeJS app!🎉

Introduction to In-built Modules

Node.js also has a large ecosystem of open-source libraries, known as "modules", which can be easily installed and used in your Node.js applications. These modules provide a wide range of functionality, from parsing HTTP requests to interacting with databases.

Node.js also has a built-in module called fs (File System) that allows you to read and write files on the server. This is useful for storing data or serving static files, such as images or CSS files.

Here is an example of how to read a file using the fs module:

const fs = require('fs');

fs.readFile('/path/to/file.txt', 'utf8', (err, data) => {
  if (err) throw err;
  console.log(data);
});

And here is an example of how to write to a file:

const fs = require('fs');

const data = 'Hello World';

fs.writeFile('/path/to/file.txt', data, 'utf8', (err) => {
  if (err) throw err;
  console.log('The file has been saved!');
});

This code will write the string "Hello World" to a file called file.txt. If the file does not exist, it will be created. If the file already exists, it will be overwritten with the new data.

In addition to its built-in modules, Node.js has a vast ecosystem of open-source libraries that can be easily installed and used in your applications. These libraries provide a wide range of functionality, from parsing HTTP requests to interacting with databases.

Best Resources to learn about NodeJS

• Documentation

• Node.js Crash Course - By Traversy Media

• Node.js Crash Course Tutorial - By The Net Ninja

• The Odin Project

By taking advantage of these resources, you can become proficient in Node.js and build sophisticated web applications that can handle a large number of concurrent connections and real-time data.

Conclusion

In conclusion, Node.js is a powerful and widely-used JavaScript runtime environment for building scalable network applications. Its event-driven, non-blocking I/O model and a large ecosystem of open-source libraries make it an excellent choice for building a wide range of web applications.