Introduction to NodeJS and Express.js

Description:

In this week, you will delve into backend development using server-side scripting with Node.js and Express.js. You will set up a basic Express.js server and create API endpoints for user authentication, expense management, and expense calculations. This will provide hands-on experience with backend development, API design, and routing using Express.js.

Requirements:

Setting up Express.js Server:

    Initialize a new Node.js project and install Express.js as a dependency.
    Create an index.js file to define the entry point for your Express.js server.
    Configure the Express.js server to listen on a specific port (e.g., 3000).
    Implement basic error handling middleware to handle server errors.

User Authentication API Endpoint:

    Create an API endpoint (POST /api/auth/login) for user authentication.
    Implement user login functionality using mock user data (e.g., username, password).
    Validate user credentials.
    Secure the authentication endpoint using appropriate security measures (e.g., password hashing).

Expense Management API Endpoints:

    Implement API endpoints for managing expenses:
        GET /api/expenses: Retrieve all expenses for a user.
        POST /api/expenses: Add a new expense for a user.
        PUT /api/expenses/:id: Update an existing expense.
        DELETE /api/expenses/:id: Delete an existing expense.

Expense Calculation API Endpoint:

    Create an API endpoint (GET /api/expense) to calculate the total expense for a user.
    Calculate the total expenses for the user based on the expense records.
    Return the total expense amount as a JSON response.

Security Considerations:

    Implement security best practices for user authentication (e.g., password hashing, JWT).
    Validate user input and sanitize data to prevent common security vulnerabilities (e.g., SQL injection, cross-site scripting).
    Secure sensitive data and API endpoints using authentication and authorization mechanisms.

Submission:

    Submit your GitHub repository for evaluation through the github classroom assignment.