Food Ordering App: Complete Checklist for Interviews

Food Ordering App: Complete Checklist for Interviews

Here is the complete checklist for building a food ordering app in a machine coding interview.

Planning (10 min)

• Read the requirements twice.
• List the required features.
• List the edge cases.
• Plan the data structure (menu array).
• Plan the state (cart object, filters, search).
• Plan the HTML structure.

Core (50 min)

• Create the menu data array.
• Render the menu list.
• Add "Add to Cart" buttons.
• Implement cart state (object: itemId -> quantity).
• Render the cart with items and quantities.
• Calculate the cart total.
• Add "Remove from Cart" functionality.
• Add quantity change (+/-) buttons.
• Implement search (filter by name).
• Implement filters (veg/non-veg, category, price).

Edge Cases (20 min)

• Handle empty cart (show message).
• Handle no search results (show message).
• Handle quantity 0 (remove from cart).
• Handle decimal prices (toFixed).
• Add clear cart button.
• Add checkout confirmation.

CSS (10 min)

• Layout: header, controls, menu grid, cart sidebar.
• Use flexbox for the main layout.
• Use grid for menu items.
• Add colors, padding, border-radius.
• Add hover states on buttons.
• Add responsive design (stack on mobile).

Testing

• Test: add items to cart.
• Test: change quantity.
• Test: remove items.
• Test: search by name.
• Test: apply filters.
• Test: empty cart state.
• Test: no results state.
• Test: checkout.
• Test: clear cart.

Follow-Up Preparation

• How to scale for 10,000 items (virtualization, server-side search).
• How to persist the cart (localStorage, backend).
• How to add authentication and payment.
• How to test (unit, integration, E2E).
• How to make it accessible (ARIA, keyboard).

The Takeaway

Checklist: plan (10 min), core (50 min: menu, cart, search, filters), edge cases (20 min: empty, no results, quantity 0), CSS (10 min: layout, grid, responsive), testing (all features and edge cases), and follow-up preparation (scaling, persistence, auth, testing, accessibility).