Use when reviewing image assets, markup, and CDN or build transforms related to Use <picture> with an <img> fallback. Check encoded size, rendered size, loading strategy, and above-the-fold impact together.
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A <picture> without an <img> fallback renders nothing in browsers that don't support <picture> (IE11) or don't support any of the <source> formats. The <img> child is also where alt, width, height, loading, and fetchpriority attributes live—these apply regardless of which source the browser selects.
<picture> must end with an <img> element—it is the required fallback and carries alt<source> elements are evaluated top-to-bottom; the first match winstype="image/avif" and type="image/webp" on <source> for format selection<img src> should point to a JPEG or PNG—the universal fallback for all browsersScan all as its last child (required fallback). 2) The
has an alt attribute. 3) The
has width and height attributes. 4)
child. 5) Each
child or with
not as the last child.
For each : add
as the last child. 2) If
is not last: move it to after all
points to a universally supported format (JPEG or PNG) as the ultimate fallback. Show the corrected
Explain how the element is the fallback for browsers that don't support
child,
, not the
Review image assets, markup, and delivery configuration related to Use fallback. Flag exact files or components where format choice, sizing, or loading behavior violates the rule, and describe how to confirm the fix in DevTools.
For full implementation details, code examples, and framework-specific guidance,
see references/rule.md.
Rule page: https://frontendchecklist.io/en/rules/images/picture-element
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