Shipping fee

Goal: write a function that turns a parcel's weight into the fee a shop charges, and gives the fee back to whoever called it.

Worked example

shippingFee(weightKg) takes the weight in kilograms and returns the fee as a number.

The price bands

A parcel of exactly 1 kg, 5 kg or 20 kg lands in the lower band.

Rules

• Write a function declaration called shippingFee that takes one parameter, weightKg.
• It must return the fee as a number. Don't print it: the code that calls your function needs the value back.
• The tests call your function many times with different weights, so it must not remember anything between calls.
• You can try it yourself by adding console.log(shippingFee(3)); at the bottom while you work, then removing it, and running node shipping_fee.js.

What you'll practice

• Writing a function declaration with a parameter
• Returning a value instead of printing it
• Choosing between several outcomes with if and else if
• Getting a boundary right with <= versus <

Run it

gonomicon fetch fs-week-2/02-01-shipping-fee
cd 02-01-shipping-fee
gonomicon test
gonomicon submit

Hints

1. Start with the function shell: function shippingFee(weightKg) { ... }. Inside, check the bands one after another with if and else if, and return a number from each one.
2. Check the heaviest or the lightest band first, and let each else if handle the next one up. Remember that a weight of exactly 1, 5 or 20 belongs to the lower band, so use <=, not <.
3. Shape: if (weightKg <= 0) { return 0; } else if (weightKg <= 1) { return 5; } else if ... and finish with return 50; for everything heavier than 20.