Function Parameters

Parameters

👨‍💼 We need utility functions for our e-commerce platform. Let's focus on functions that accept clear inputs and return the right type.

🐨 Open

index.ts

and create these exported functions with typed parameters and explicit return types:

calculateTax(amount: number, rate: number): number — returns the tax amount for the given amount and rate. Examples: calculateTax(100, 0.08) → 8; calculateTax(50, 0.1) → 5
formatPrice(cents: number): string — converts whole cents into a dollar string with a $ prefix and exactly two decimal places. Examples: formatPrice(1999) → "$19.99"; formatPrice(100) → "$1.00"; formatPrice(50) → "$0.50"
applyDiscount(price: number, discountPercent: number): number — returns the price after a percentage discount is applied. Examples: applyDiscount(100, 20) → 80; applyDiscount(50, 10) → 45; applyDiscount(200, 25) → 150

Required exports

calculateTax, formatPrice, applyDiscount

The examples above must all pass. Prefer keeping return types explicit even though this step focuses on parameter types.