Express.js Mastery / Introduction To Node.js And NPM

Core Modules

🛠️ Prerequisites

Make sure the 1-node-farm starter folder is open. If you're currently in the project root, please open that folder instead.

📝 Step 1: Create a New JavaScript File

  1. In the root folder of your project, create a new file named:

index.js

✍️ Step 2: Write Your First Node Code

Inside index.js, write:

const hello="Hello world!";
console.log(hello);

  • This creates a variable called hello storing the classic "Hello world" text
    (traditionally the first thing written when learning any new programming language).

  • console.log() prints the value to the terminal.

  • Save the file.

▶️ Step 3: Run the File Using Node

  • Unlike browser JavaScript (where you'd link the file inside an HTML page and open it in a browser), Node lets you run JavaScript files directly from the terminal.

  • In the terminal, type:

node index.js

and press Enter.

  • Important: don't just type node and press Enter alone — that opens the REPL instead. You must include the filename right after node.

  • Output:

Hello world!

🎉 This means you've successfully run your first Node.js script.

🧐 Understanding Node Modules

  • Node.js can do things browser JavaScript cannot — like reading and writing files from the computer's file system.

  • This functionality is not built into plain JavaScript — it comes from Node modules.

  • For file operations, Node provides a built-in module called FS (File System).

📥 Importing (Requiring) a Module

To use a module, you require it and store the result in a variable:

const fs = require('fs');

  • require('fs') loads the File System module.

  • The result (an object containing many useful functions for reading/writing files) is stored in the fs variable.

  • This fs variable will be used in the next step of the course to actually read files.

📚 Learning to Use the Node Documentation

Whenever you need info about a module or function, refer to the official Node.js documentation:

  1. 🌐 Go to nodejs.org

  2. 📖 Click the Documentation tab.

  1. 📂 On the left side, you'll see a list of all built-in modules, such as:

    • 🖥️ REPL (used earlier)

    • 📁 File System (fs) (used in this note)

    • 📦 Many others


📖 Reading the Docs

  • Each module page covers its functions, parameters, and examples.

  • Example: to read a file, look up fs.readFileSync() — we'll use this next.

  • It's okay if the docs feel confusing at first; it'll click as you go.

🎯 Key Takeaways

  • You can write and run standalone .js files using the command:

node filename.js

  • Node's extra capabilities (like file handling) come from modules, which you load using require().

  • The official Node.js documentation is the go-to resource for learning about any built-in module or function.

  • Next step: Actually use the fs module to read a file from disk using fs.readFileSync().