---
title: "Rith Banerjee (@rithcoderr) | Hashnode"
description: "learn code. Read the latest articles by Rith Banerjee on Hashnode."
url: "https://hashnode.com/@rithcoderr"
---

@rithcoderr

# Rith Banerjee

@rithcoderr · Joined August 2025

learn code

### [How WhatsApp Works Without Internet: Offline Messaging and Sync Explained](https://blog.rithbanerjee.site/how-whatsapp-works-without-internet-offline-messaging-and-sync-explained?utm_source=hashnode&utm_medium=feed)

You are on a flight. Airplane mode is on. You text your friend. The app doesn't crash. It shows a clock icon. Later, you land. The message sends. How? Internet is unreliable. Tunnels, elevators, bad c

3 min read · [blog.rithbanerjee.site](https://blog.rithbanerjee.site/how-whatsapp-works-without-internet-offline-messaging-and-sync-explained?utm_source=hashnode&utm_medium=feed)

[May 31](https://hashnode.com/posts/how-whatsapp-works-without-internet-offline-messaging-and-sync-explained/6a1c53a269c80d28f6504da3)

### [How React Virtual DOM Works Under the Hood](https://blog.rithbanerjee.site/how-react-virtual-dom-works-under-the-hood?utm_source=hashnode&utm_medium=feed)

Direct DOM manipulation is slow. Updating the screen directly forces the browser to recalculate layouts and repaint pixels. Do this too often, your app lags. React solves this. How? The Virtual DOM. T

3 min read · [blog.rithbanerjee.site](https://blog.rithbanerjee.site/how-react-virtual-dom-works-under-the-hood?utm_source=hashnode&utm_medium=feed)

[May 31](https://hashnode.com/posts/how-react-virtual-dom-works-under-the-hood/6a1c531971856a58b0dbaefa)

### [How Instagram, WhatsApp, Uber & Netflix Would Be Built Today Using Expo Router](https://blog.rithbanerjee.site/how-instagram-whatsapp-uber-netflix-would-be-built-today-using-expo-router?utm_source=hashnode&utm_medium=feed)

Building a todo app is easy. Building Instagram is hard. The difference isn't the code. It's the architecture. Let's look at how massive mobile apps scale using React Native and Expo Router. No fluff.

4 min read · [blog.rithbanerjee.site](https://blog.rithbanerjee.site/how-instagram-whatsapp-uber-netflix-would-be-built-today-using-expo-router?utm_source=hashnode&utm_medium=feed)

[May 31](https://hashnode.com/posts/how-instagram-whatsapp-uber-netflix-would-be-built-today-using-expo-router/6a1c521a71856a58b0db0e45)

### [JavaScript Modules: Import and Export Explained](https://blog.rithbanerjee.site/javascript-modules-import-export-explained?utm_source=hashnode&utm_medium=feed)

Learn JavaScript modules with clear import & export examples. Master default vs named exports, avoid common mistakes, and write cleaner, scalable code

6 min read · [blog.rithbanerjee.site](https://blog.rithbanerjee.site/javascript-modules-import-export-explained?utm_source=hashnode&utm_medium=feed)

[3](https://hashnode.com/posts/javascript-modules-import-export-explained/69f21f4a6e0124c05e23cd6e) [Apr 29](https://hashnode.com/posts/javascript-modules-import-export-explained/69f21f4a6e0124c05e23cd6e)

### [Async Code in Node.js: Callbacks and Promises](https://blog.rithbanerjee.site/async-code-nodejs-callbacks-and-promises?utm_source=hashnode&utm_medium=feed)

Discover how async code works in Node.js. Learn callbacks, avoid callback hell, and master promises with clear, beginner-friendly examples.

8 min read · [blog.rithbanerjee.site](https://blog.rithbanerjee.site/async-code-nodejs-callbacks-and-promises?utm_source=hashnode&utm_medium=feed)

[Apr 29](https://hashnode.com/posts/async-code-nodejs-callbacks-and-promises/69f218526e0124c05e1dba0e)