Extras/Muffin Shop Dashboard

Business rules

• Money display: formatMoney formats an amount with a leading $ (for example 4.5 displays as $4.5).
• Line items: buildLineItemText shows quantity x name, and appends (GF) (leading space) when the item is gluten-free. Examples: 2 x Blueberry Muffin, 1 x Oatberry Muffin (GF).
• Subtotal: sum of each item’s price × quantity (use a loop).
• Member discount: status 'member' gets 10% off when the subtotal is at least $20; otherwise $0.
• Tax / tip: tax uses the taxable amount and rate; tip uses the amount before tip and the tip percent.
• Total: subtotal, minus discount, plus tax, tip, and pickup fee.
• Pickup fee (switch): counter → $0, curbside → $3, delivery → $7.
• Pickup label (switch): Counter pickup, Curbside pickup, or Delivery dropoff. Use assertNever for impossible cases.
• Notes: null or an empty string becomes No special notes; otherwise keep the note.
• Ready log: logOrderReady is a void function that logs Order ready for <customer>.
• assertNever: throw so TypeScript knows that branch cannot continue (include the unexpected value in the error).

Success criteria

• The dashboard in
  src/app.tsx
  renders without runtime errors once the helpers are implemented
• With the default app fixtures (member, curbside, gluten-free items, empty note), you should see:
  • Line items including a (GF) suffix where appropriate
  • Pickup label Curbside pickup and a pickup fee of $3
  • Special note text No special notes
  • Console log: Order ready for Avery
• Toggle memberStatus or pickupMethod in
  src/app.tsx
  and confirm labels/fees/discounts update

Run the example

npm run dev --workspace extra_muffin-shop-dashboard

Try next

• 🐨 Add another OrderItem and watch the totals change.
• 🐨 Add a rushOrder boolean and increase the tip when it is true.
• 🐨 Add a itemCount helper that uses a loop to count total quantity.
• 🐨 Add a happyHour boolean and reduce the muffin price when true.
• 🐨 Add a memberMessage string in app.tsx using an if check.
• 💰 Change specialNote to a real note and confirm the fallback logic.