Test Assignment: Order Price Calculation with Discounts and Taxes

Description

Your team is developing an e-commerce platform. Your task is to implement a function that calculates the final price of an order, considering possible discounts and taxes.

Technical Requirements

Implement a function calculateTotal(order), which takes an order object as input and returns a number representing the final order price.

Important Rules

• The assignment and the provided code must be written in pure JavaScript (no external libraries).
• The code must not throw throw Error under any circumstances.
• If any input values are invalid, they should be treated as 0.

Input Structure

The input is an object with the following structure:

{
  items: [  // array of items in the order
    { price: 100, quantity: 2 }, // item costing 100, quantity 2
    { price: 200, quantity: 1 }
  ],
  discount: { type: "percentage", value: 10 }, // 10% discount
  tax: 7 // 7% tax (applied after discount)
}

Supported Discount Types

• "fixed" — a fixed discount amount, e.g., { type: "fixed", value: 50 }
• "percentage" — a percentage-based discount, e.g., { type: "percentage", value: 10 } (10% off the total amount)

Tax (tax) is applied after all discounts.

Additional Conditions

• The input data may be incorrect (negative prices, invalid discount values)
• The function should handle edge cases correctly
• The final result should be rounded to two decimal places
• You must not modify parameter names or the structure of the input object

Expected Output

The function must return the final order total as a number.

Example Call

order = {
    items: [
      { price: 100, quantity: 2 },
      { price: 200, quantity: 1 }
    ],
    discount: { type: "percentage", value: 10 },
    tax: 7
  }
calculateTotal(order);
// Expected result: 385.20

Calculation Steps

1. Calculate the initial total (sum of price × quantity for all items)
2. Apply discount if present:
   • For fixed discount: subtract the discount amount
   • For percentage discount: subtract the percentage from the total
3. Apply tax to the discounted amount
4. Round the final result to 2 decimal places (if needed)

Evaluation Criteria

• Understanding Requirements: How well discounts and taxes are handled
• Code Quality: Readability, cleanliness, and adherence to JavaScript best practices
• Edge Cases Handling: Processing of invalid and edge-case inputs

Submission Guidelines

1. Implement only the calculateTotal(order) function
2. Submit your solution in a .txt text file
3. Name the file using the following format: your_name.txt
4. Our team will run predefined tests against your function
5. Ensure the function correctly passes all test cases

Example Solution Template

function calculateTotal(order) {
  // Your implementation here
}

Good luck!