# What is Node.js? JavaScript on the Server Explained


## What Is Node.js

Node.js Is cross platform ,open Source Cross platform javaScript Run Time Environment that allow you to run JavaScript on the Server-side ,outside the browser . It's built on Chrome's V8 JavaScript engine, which makes it fast and efficient for building scalable and high-performance network applications

## Why JavaScript was originally browser-only .

The JavaScript is added solely 1995 to add interactivity to the Web page .

So browser isolated javascript in a strict sandbox for security reasons.

No OS access : It could not access the local file system, network interfaces, or hardware.

Early engines were slow interpreters designed only for basic browser scripts .

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## How Node.js made JavaScript run on servers

In 2009 Ryan Dhal took Google Open Source V8 engine out of the Browser And embed it inside C++ program called Node.js .

*   **System Access**: Dahl added low-level C++ APIs to handle file systems and networking.
    
*   **Unified Interface**: He exposed these C++ capabilities to JavaScript.
    
*   **Single Language**: This allowed JavaScript to run directly on an operating system like a standard backend language.
    

## V8 engine overview

Google V8 is a high-performance, open-source JavaScript engine written in C++. It compiles human-readable JavaScript directly into native machine code before executing it.

## Event-driven architecture idea

Node.js uses an event-driven architecture to handle high concurrency with a single execution thread .

Instead of assigning a new thread to every incoming connection, Node.js triggers an event when an operation starts. It then moves on to the next task immediately. When the background operation finishes, it emits a completion event that triggers the corresponding callback function.

## Real-world use cases of Node.js :-

*   Rest API & Microservices .
    
*   Streaming Services.
    
*   Single Page Application .
    
*   Real Time Application