Use srcset for responsive images
Without srcset, every user—regardless of their device—downloads the same large image. A 1600px hero image served to a 375px mobile display downloads 4x the data needed. The srcset attribute lets browsers choose the optimal file automatically, reducing bandwidth by 50-80% for mobile users with no change to visual quality.
Quick Reference
- Add
srcsetwith width descriptors (400w,800w) to all images wider than ~100px - Always pair
srcsetwidth descriptors with asizesattribute—withoutsizesthe browser assumes100vw - Use density descriptors (
1x,2x) only for fixed-size images like avatars and icons - Keep
srcpointing to a fallback size for browsers that don't supportsrcset
Check
Scan all <img> elements in this codebase. Flag: 1) Any <img> wider than 100px (in CSS or layout) that lacks a srcset attribute. 2) Any <img> with srcset but missing a sizes attribute (necessary for width descriptors). 3) Any <img> using only density descriptors (1x, 2x) where width descriptors (400w, 800w) would be more appropriate. 4) Any srcset that provides only one size (no benefit over plain src). Report each finding with file p…