🧮 Project Algebra – Personalized Calculator System

📌 Overview

Project Algebra is a stateful web-based calculator application that enables users to securely perform calculations while maintaining a personalized history. The system is designed to demonstrate core backend engineering concepts such as authentication, session management, and persistent data handling without relying on traditional database systems.

🚀 Key Features

• Session-Based Authentication: Secure user login and session handling using Express.js
• User-Specific Data Isolation: Each user maintains an independent calculation history
• File-Based Persistence: Data is stored and managed using a JSON file system
• Asynchronous Data Handling: Non-blocking file operations for efficient data updates
• Route Protection: Middleware-based access control for secured endpoints
• Dynamic History Filtering:
  • Today and Yesterday
  • Weekly and Monthly views
  • Custom date-based filtering
• State Synchronization: Consistent data flow between session storage and persistent storage

🧠 Design Rationale

This project intentionally avoids the use of databases such as MongoDB to focus on understanding low-level data management. By implementing file-based storage, the system explores:

• Asynchronous file handling mechanisms
• Data writing and retrieval processes
• Manual management of persistent application state

This approach strengthens foundational backend concepts often abstracted away by database systems.

🛠️ Technology Stack

• Backend: Node.js, Express.js
• Frontend: HTML, CSS, JavaScript
• Storage: JSON (File System)
• Authentication: express-session