E-Commerce Development Mobile Commerce 5 — Questions and Answers
Question 1: A mobile store's images are sharp on standard displays but appear blurry on high-DPI (Retina) screens. What is the best fix?
- Use srcset to serve 2x and 3x resolution images based on device pixel ratio (Correct answer)
- Always serve 4K images regardless of device
- Use CSS zoom: 2 on all images
- Disable image compression for mobile
Correct answer: Use srcset to serve 2x and 3x resolution images based on device pixel ratio
The srcset attribute lets the browser select the appropriately sized image based on the device's pixel ratio, balancing clarity and bandwidth.
Question 2: Which feature of Accelerated Mobile Pages (AMP) historically improved mobile page speed but has been deprecated by Google as a ranking factor?
- AMP cache pre-rendering in Google Search (Correct answer)
- AMP JavaScript components
- AMP image placeholders
- AMP analytics tags
Correct answer: AMP cache pre-rendering in Google Search
Google's AMP cache served pre-rendered pages from Google's CDN, but Google removed AMP as a Top Stories eligibility requirement in 2021.
Question 3: What does 'biometric authentication' allow in a mobile commerce checkout flow?
- Users confirm payment with fingerprint or Face ID instead of a password (Correct answer)
- The app scans the payment card via camera
- The server verifies the user's geographic location
- The device checks shipping address via GPS
Correct answer: Users confirm payment with fingerprint or Face ID instead of a password
Biometric auth uses the device's secure enclave to authenticate users via fingerprint or facial recognition, replacing password entry at checkout.
Question 4: Which mobile commerce pattern shows a condensed product grid on first load and expands details inline without a page reload?
- Expandable/accordion product cards (Correct answer)
- Modal overlay checkout
- Infinite scroll pagination
- Skeleton screen loading
Correct answer: Expandable/accordion product cards
Accordion cards reveal additional product info (size, color, description) inline, reducing navigation and keeping the user in context.
Question 5: A developer wants to detect whether a user is on a mobile device within a JavaScript bundle. What is the most reliable method?
- Check window.matchMedia('(pointer: coarse)') or screen width (Correct answer)
- Check navigator.userAgent for 'Mobile' string
- Check if touch events exist via 'ontouchstart' in window only
- Use navigator.platform === 'iPhone'
Correct answer: Check window.matchMedia('(pointer: coarse)') or screen width
matchMedia('(pointer: coarse)') detects touch-primary input devices accurately without relying on fragile user-agent strings.
Question 6: Which mobile checkout optimization has been proven to reduce form abandonment by letting users skip form fields for returning customers?
- One-click / express checkout (e.g., Shop Pay, PayPal Express) (Correct answer)
- Requiring full form re-entry for security
- Removing the save-card option to reduce friction
- Splitting checkout into 6 separate pages
Correct answer: One-click / express checkout (e.g., Shop Pay, PayPal Express)
Express checkout solutions pre-fill shipping and payment from stored profiles, cutting checkout to a single confirmation tap for returning users.
Question 7: In mobile e-commerce, what is 'conversational commerce'?
- Selling products through chat interfaces like SMS, WhatsApp, or chatbots (Correct answer)
- A/B testing product descriptions for tone
- Voice search SEO optimization
- Live streaming product demos
Correct answer: Selling products through chat interfaces like SMS, WhatsApp, or chatbots
Conversational commerce uses messaging platforms and AI chatbots to guide customers through product discovery, questions, and purchase within a chat thread.
E-Commerce Development Mobile Commerce 5
A mobile store's images are sharp on standard displays but appear blurry on high-DPI (Retina) screens.
What is the best fix?