Understanding Node.js Internals

1. Introduction

Node.js is a runtime environment that allows you to run JavaScript on the server side. This lesson will cover the fundamental internals of Node.js, focusing on the Event Loop, V8 Engine, Libuv, and Module system.

2. The Event Loop

The Event Loop is a core feature of Node.js that allows it to perform non-blocking I/O operations.

Here’s a simplified depiction of the Event Loop:

graph TD;
    A[Start] --> B[Check Call Stack];
    B -->|Empty| C[Check Event Queue];
    C -->|Tasks Available| D[Execute Task];
    D --> B;
    C -->|No Tasks| B;
    B --> A;
            

This loop continues until there are no more tasks to execute.

3. V8 Engine

The V8 Engine is the JavaScript engine used by Node.js. It compiles JavaScript to native machine code, which increases performance.

Key features of the V8 Engine include:

• Just-in-time (JIT) compilation
• Garbage collection
• Optimized memory management

4. Libuv

Libuv is a multi-platform support library that focuses on asynchronous I/O. It provides the underlying mechanisms for the Event Loop.

Libuv abstracts various OS-specific features such as:

• File system operations
• Networking
• Thread pooling

5. Modules

Node.js uses a module system to encapsulate code. Modules can be imported and exported using the CommonJS module syntax.

Example:

// mymodule.js
exports.sayHello = function() {
    console.log("Hello, World!");
};

// app.js
const myModule = require('./mymodule');
myModule.sayHello(); // Outputs: Hello, World!
                

Modules play a crucial role in structuring Node.js applications.

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