Introduction to NodeJS

NodeJS is a JavaScript Runtime that run JS without browser. (Run JS on server)

2. Node.js Architecture

Here’s the magic behind Node.js — it’s single-threaded but non-blocking, thanks to the Event Loop.

Event Loop

The Event Loop is a mechanism that handles:

Single Threaded

Node.js uses a single thread for JavaScript execution but uses libuv (a C++ library under the hood) to manage background tasks on a thread pool.

Non-blocking I/O

Node.js doesn’t block the main thread while doing I/O operations like file or database access.

So instead of this (in PHP):

$data = file_get_contents("bigfile.txt"); // blocks the script

Nodejs does this

fs.readFile("bigfile.txt", (err, data) => {
  if (err) throw err;
  console.log(data.toString());
});

→ It runs asynchronously, letting Node handle other requests while the file is loading.