MKMohit Kumarinimohit1o1.hashnode.dev·May 31 · 6 min readHow WhatsApp Works Without Internet: Offline Messaging and Sync Explained"Message bheja. Internet tha nahi. Phir bhi sent dikh gaya. Kaise?" You type a message. Hit send. Airplane mode is on. The message appears in the chat. "Sent" shows up. But there's no internet. Magic00
MKMohit Kumarinimohit1o1.hashnode.dev·May 31 · 6 min readHow Instagram Stores Reels, Photos, and Drafts Behind the ScenesYou record a Reel. Add a filter. Save it as draft. Close the app. Open it tomorrow. Draft is still there. Magic? No. Smart engineering. Let me explain what happens behind the screen. The Journey of a00
MKMohit Kumarinimohit1o1.hashnode.dev·May 10 · 6 min readString Polyfills and Common Interview Methods"Understanding a method is one thing. Implementing it is another." You know "hello".toUpperCase() gives "HELLO". You know trim() removes spaces. But do you know how? Interviews ask: "Write your own v00
MKMohit Kumarinimohit1o1.hashnode.dev·May 10 · 6 min readHandling File Uploads in Express with MulterYou have a form. User wants to upload a profile picture. Regular JSON won't work. Files need special handling. Express can't read files directly. You need middleware. Let me show you how with Multer. 00
MKMohit Kumarinimohit1o1.hashnode.dev·May 10 · 6 min readREST API Design Made Simple with Express.js You have a server. You want to talk to it from your frontend. But how? Where do you start? GET, POST, PUT, DELETE – sounds confusing. Let me simplify REST APIs with one example: users. What REST API 00
