1. What is Node.js? #

Node.js is a runtime environment that allows you to execute JavaScript code on the server-side. It's built on the Chrome V8 JavaScript engine and provides a set of non-blocking I/O libraries that make it efficient and lightweight. Node.js is used for building server-side applications, including web servers, APIs, and more.

2. Installing Node.js #

To get started with Node.js, you need to install it on your system. Visit the official Node.js website to download the installer for your operating system and follow the installation instructions.

3. Hello, Node.js! #

After installation, open your terminal or command prompt and run the following command to check if Node.js is installed correctly:

node -v

This command will display the installed Node.js version. Now, let's create a simple "Hello, Node.js!" script:

// hello.js
console.log("Hello, Node.js!");

Run the script using the following command:

node hello.js

You should see the "Hello, Node.js!" message printed in the terminal.

4. Core Modules in Node.js #

Node.js comes with several built-in modules that you can use in your applications. For example, the fs module allows you to work with the file system, and the http module helps you create HTTP servers. Here's an example of using the fs module to read a file:

const fs = require('fs');

fs.readFile('example.txt', 'utf8', (err, data) => {
  if (err) {
    console.error(err);
    return;
  }
  console.log(data);
});

5. Creating and Running Node.js Scripts #

Node.js allows you to create and run JavaScript scripts easily. You can use it for various tasks, such as data processing and automation. Here's an example of a simple script that calculates the sum of numbers:

function sumNumbers(numbers) {
  return numbers.reduce((acc, num) => acc + num, 0);
}

const numbers = [1, 2, 3, 4, 5];
console.log(`Sum of numbers: ${sumNumbers(numbers)}`);

Run the script using:

node sum.js

6. Node.js Package Management with npm #

Node.js comes with a package manager called npm (Node Package Manager) that allows you to install, manage, and share packages (libraries) with the Node.js community. You can start a new project by creating a package.json file and installing packages. For example:

npm init  # Follow the prompts to create a package.json file
npm install express  # Install the Express.js framework

7. Node.js Asynchronous Programming #

Node.js is known for its non-blocking, asynchronous programming model. It uses callbacks, Promises, and async/await to handle asynchronous operations efficiently. For example, using Promises:

const fetchData = () => {
  return new Promise((resolve, reject) => {
    setTimeout(() => {
      resolve("Data received!");
    }, 2000);
  });
};

fetchData()
  .then((data) => {
    console.log(data);
  })
  .catch((error) => {
    console.error(error);
  });

8. Conclusion and Next Steps #

This tutorial provides a brief introduction to Node.js, including installation, creating scripts, and using core modules. Node.js is a versatile technology with numerous use cases, and it serves as the foundation for building server-side applications and APIs.

In the next section of your course, you can explore Express.js, a popular framework for building web servers and APIs using Node.js. Express.js simplifies routing, middleware, and request handling, making it a powerful tool for web development. If you're ready to continue with the Express.js lesson, please let me know, and I'll provide a detailed tutorial for that as well.

get started with Node.Js