--- title: "Pankaj Kumar (@pankajkry) | Hashnode" description: "Pankaj Kumar (@pankajkry) writes on Hashnode. Read their latest articles and follow their work." url: "https://hashnode.com/@pankajkry" --- @pankajkry # Pankaj Kumar @pankajkry · Joined December 2024 ### [How WhatsApp Works Without Internet: Offline Messaging and Sync Explained](https://mobile-dev-expo.hashnode.dev/how-whatsapp-works-without-internet-offline-messaging-and-sync-explained?utm_source=hashnode&utm_medium=feed) Introduction Imagine you're on a flight with Airplane Mode enabled. You open WhatsApp, type a message to your friend, and press Send. Surprisingly, the message immediately appears in your chat window. 7 min read · [mobile-dev-expo.hashnode.dev](https://mobile-dev-expo.hashnode.dev/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/6a1b8f9d2d59948cf6b0001d) ### [How Instagram, WhatsApp, Uber & Netflix Would Be Built Today Using Expo Router](https://mobile-dev-expo.hashnode.dev/how-instagram-whatsapp-uber-netflix-would-be-built-today-using-expo-router?utm_source=hashnode&utm_medium=feed) Introduction Modern mobile applications are no longer simple collections of screens connected together. Apps like Instagram, WhatsApp, Uber, and Netflix serve millions of users simultaneously while ha 12 min read · [mobile-dev-expo.hashnode.dev](https://mobile-dev-expo.hashnode.dev/how-instagram-whatsapp-uber-netflix-would-be-built-today-using-expo-router?utm_source=hashnode&utm_medium=feed) [May 23](https://hashnode.com/posts/how-instagram-whatsapp-uber-netflix-would-be-built-today-using-expo-router/6a113ada1f237623ea6aa8a8) ### [React Native Routing: React Navigation vs Expo Router](https://mobile-dev-expo.hashnode.dev/react-native-routing-react-navigation-vs-expo-router?utm_source=hashnode&utm_medium=feed) Routing in mobile apps is one of those topics that feels simple at first: “Move from Screen A to Screen B.” But in real applications, navigation becomes much deeper: authentication flows nested ta 8 min read · [mobile-dev-expo.hashnode.dev](https://mobile-dev-expo.hashnode.dev/react-native-routing-react-navigation-vs-expo-router?utm_source=hashnode&utm_medium=feed) [May 23](https://hashnode.com/posts/react-native-routing-react-navigation-vs-expo-router/6a1128651f237623ea5f69d0) ### [How React Virtual DOM works under the Hood](https://mobile-dev-expo.hashnode.dev/how-react-virtual-dom-works-under-the-hood?utm_source=hashnode&utm_medium=feed) Before going to Virtual DOM lets understand DOM First DOM : Document Object Model Dom is a programming interface for HTML and XML documents that represents a web page as a trees of objects. Each par 7 min read · [mobile-dev-expo.hashnode.dev](https://mobile-dev-expo.hashnode.dev/how-react-virtual-dom-works-under-the-hood?utm_source=hashnode&utm_medium=feed) [May 8](https://hashnode.com/posts/how-react-virtual-dom-works-under-the-hood/69fe2f3ef239332df4fc5703) ### [Nodejs Deployment on VPS with Github Action](https://pankajkry.hashnode.dev/nodejs-deployment-on-vps-with-github-action?utm_source=hashnode&utm_medium=feed) A quick guide to deploying a Node.js app on a VPS using Docker and automating updates with GitHub Actions for seamless CI/CD. Let’s understand how to deploy a project to a server.” Without Github Ac 6 min read · [pankajkry.hashnode.dev](https://pankajkry.hashnode.dev/nodejs-deployment-on-vps-with-github-action?utm_source=hashnode&utm_medium=feed) [May 3](https://hashnode.com/posts/nodejs-deployment-on-vps-with-github-action/69f7839276c1469ba4d17ea6)