added md file

Author: Kanavpreet-Singh

assets/expense-tracker-preview.png

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+# 💰 Expense Tracker
+
+![Expense Tracker Preview](../../assets/expense-tracker-preview.png)
+
+## Description
+
+A simple **Expense Tracker** built using **HTML, CSS, and JavaScript (ES Modules)** that allows users to manage their daily income and expenses. Users can **add, edit, and delete** transactions, view their **balance summary**, and store data locally using **localStorage** — all without a backend.
+
+## Features
+
+- Add new transactions (income or expense)  
+- Edit existing transactions  
+- Delete unwanted transactions  
+- View total balance, income, and expense summaries  
+- Persistent data storage using `localStorage`  
+- Clean and responsive UI design  
+
+## Concepts Practiced
+
+- DOM manipulation  
+- Working with arrays and objects  
+- Event handling and form submission  
+- Data persistence using `localStorage`  
+- Conditional rendering and dynamic UI updates  
+- Modular JavaScript (`index.mjs`)  
+
+## Bonus Challenge
+
+- Add a **dark mode toggle** in the navbar 🌙  
+- Show a **monthly expense chart** using a JS chart library  
+- Add a **filter/search** option for transactions  
+- Allow users to **export data** as CSV  
+
+## Live Demo
+
+<div align="center">
+<iframe src="https://codesandbox.io/p/sandbox/f9n98v"
+     style="width:100%; height: 500px; border:0; border-radius: 4px; overflow:hidden;"
+     title="expense-tracker"
+     allow="accelerometer; ambient-light-sensor; camera; encrypted-media; geolocation; gyroscope; hid; microphone; midi; payment; usb; vr; xr-spatial-tracking"
+     sandbox="allow-forms allow-modals allow-popups allow-presentation allow-same-origin allow-scripts"
+></iframe>
+</div>