E-Commerce Development Mobile Commerce 5

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?

Accepted Answer

Use srcset to serve 2x and 3x resolution images based on device pixel ratio

Answer

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?

Accepted Answer

AMP cache pre-rendering in Google Search

Answer

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?

Accepted Answer

Users confirm payment with fingerprint or Face ID instead of a password

Answer

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?

Accepted Answer

Expandable/accordion product cards

Answer

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?

Accepted Answer

Check window.matchMedia('(pointer: coarse)') or screen width

Answer

matchMedia('(pointer: coarse)') detects touch-primary input devices accurately without relying on fragile user-agent strings.

E-Commerce Development Practice Test