Let and Const

👨‍💼 We're building a shopping cart system. Some values will change as users interact (like the cart total), while others stay constant (like tax rates and product prices).

🐨 Open

index.ts

and:

Create a const named TAX_RATE set to 0.08
Create a let named cartTotal starting at 0
Create const product prices with these exact values:
- bookPrice = 15.99
- muffinPrice = 4.5
- laptopPrice = 999.99
Add the book and the muffin to the cart by updating cartTotal (do not add the laptop for this step)
Create finalTotal as the cart subtotal plus 8% tax (TAX_RATE)
Try to reassign TAX_RATE (keep it commented after you see the TypeScript error) and export your results

Required exports

Export these names so the tests can verify your work:

TAX_RATE
cartTotal
finalTotal

Completion criteria (with the fixtures above)

TAX_RATE is 0.08
cartTotal is 20.49 (book + muffin only)
finalTotal is 22.1292 (subtotal + 8% tax)

💰 By convention, constants that represent fixed values are often UPPER_CASE:

const MAX_ITEMS = 100
const API_URL = 'https://api.example.com'

📜 MDN - const

This is the first exercise where you'll be exporting values for the tests! For a reminder on how to do that, check out the previous page.

02. Variables and Immutability/01. Let and Const (💪 problem)

Let and Const

Required exports

Completion criteria (with the fixtures above)