Lambda

A lightweight, X/Twitter-style clone app built with the MERN stack. Create posts, follow people, like content, and browse a personalized feed — all with JWT auth and a responsive, Tailwind-powered UI. 🚀

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Tech Stack

Frontend

• React 19 + Vite 7
• React Router
• Tailwind CSS (v4 integration via @tailwindcss/vite) + DaisyUI utility classes
• Axios (with auth interceptor & baseURL from VITE_API_URL)
• ErrorBoundary + protected route guards

Backend

• Node.js + Express 5
• MongoDB + Mongoose 8
• JWT (jsonwebtoken) for auth
• bcryptjs for password hashing
• CORS, dotenv
• Seed script powered by @faker-js/faker

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Features

Auth & Account

• Register with username + email + password
• Login via email or username + password
• JWT-based sessions; /auth/me for current user
• Local storage persistence and auto-injected Authorization header via Axios interceptor 🔐
• Update profile bio (PUT /users/profile)

Social Graph

• Follow / Unfollow users (PUT /users/:id/follow)
• Followers / following counts and modals (/users/:id/followers, /users/:id/following)
• Popular Users sidebar — ranked by postCount + totalLikes (aggregation pipeline)

Posts

• Create & delete your own posts
• Like / Unlike posts (PUT /posts/:id/like) with live counts
• Personalized feed (GET /posts/feed) for you + people you follow (fallback to all posts if needed)
• View user’s posts and liked posts
• @mentions in post text are clickable and route to /user/:username

Search & Navigation

• Debounced user search (/users/search/:query)
• Clean, responsive layout with a mobile bottom nav
• Safe UX: Loading states, toasts/messages, and an Error Boundary for runtime errors

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Scripts

Client

• npm run dev – start Vite dev server
• npm run build – production build
• npm run preview – preview built app

Server

• npm run dev – start API with nodemon
• npm run seed – seed DB (users, follows, posts, likes)
• npm run seed:purge – purge & reseed

Seeding Notes

• All seeded users share the password: password123
• Counts and probabilities are configurable via SEED_* envs
• After seeding, you can log in with any generated username/email (check DB or Popular Users list for names)

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Running Locally

1. In server/: create .env (see above), then:

   npm install
   npm run seed
   npm run dev

2. In client/: create .env (see above), then:

   npm install
   npm run dev

3. Open the client URL (Vite will print it) and log in or register.

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Notes & Decisions

• Likes are tracked both as an array (likes) and a denormalized count (likeCount) for efficiency.
• The feed endpoint returns posts from you + following, newest first, capped to 20 (client gracefully falls back to /posts).
• Popular users are computed via aggregation: score = postCount + totalLikes.
• UI uses Tailwind utility classes (with DaisyUI classnames like btn) for fast iteration. 🎯

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This repo was built as a learning/practice project