Review picture elements that select images by format or display conditions. Check fallback images, alternative text, dimensions, and source ordering, then provide corrected HTML with JPEG or PNG fallbacks for browsers that cannot use the selected formats.
中文简介正在准备中。当前显示英语简介。
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.
安装前可以查看交给 AI 代理的指令内容。
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 <picture> elements in this codebase. Verify: 1) Every <picture> has an <img> as its last child (required fallback). 2) The <img> has an alt attribute. 3) The <img> has width and height attributes. 4) <source> elements appear before the <img> child. 5) Each <source> has either a srcset attribute or a media attribute. 6) format-selecting <source> elements have a type attribute (type="image/avif", type="image/webp"). Flag any <picture> missing an <img> child or with <img> not as the last child.
For each <picture> element with issues: 1) If missing <img>: add <img src="{fallback-url}" alt="{description}" width="{w}" height="{h}"> as the last child. 2) If <img> is not last: move it to after all <source> elements. 3) If <source> elements lack type attributes for format selection: add type="image/avif" or type="image/webp". 4) Verify the <img src> points to a universally supported format (JPEG or PNG) as the ultimate fallback. Show the corrected <picture> markup.
Explain how the <picture> element works. Browsers evaluate <source> elements in document order and use the first one whose conditions match (type, media, srcset). The <img> element is the fallback for browsers that don't support <picture> (IE11) or don't support the source format. Without an <img> child, <picture> is invalid HTML and produces no output. The alt attribute must be on the <img>, not the <source> elements—it applies regardless of which source is selected.
Review image assets, markup, and delivery configuration related to Use <picture> with an <img> 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/rules/images/picture-element
还没有评价。欢迎分享你的使用感受。
无需登录即可发表。欢迎分享使用感受、提问，或说明在哪些环境下无法运行。
还没有评论。来写第一条吧。
Create and review custom 404 pages that help visitors recover from broken or moved links through search and navigation. Check the rendered page and HTTP response so missing content returns a proper 404 status.
中文简介正在准备中。当前显示英语简介。
Audit or create a dedicated About page that explains a website’s purpose and identifies its people or organization. Review the rendered output and supporting information, including expertise and contact details, to find gaps.
中文简介正在准备中。当前显示英语简介。
Review and add automated accessibility checks for components, pages, and continuous integration workflows. Use axe-based tools to detect structural and attribute issues, while identifying checks that still need keyboard or screen reader testing.
中文简介正在准备中。当前显示英语简介。
Review sign-in, registration, multi-factor authentication, and account recovery for accessibility barriers. Find blocked paste, difficult code entry, and inaccessible backup methods, then suggest authentication paths that support password managers, autofill, or device approval.
中文简介正在准备中。当前显示英语简介。
Review form errors, success messages, and live updates so screen reader users receive important notifications. Check the HTML delivered to the browser, announcement settings, display duration, and dismissal controls, then identify specific elements that need changes.
中文简介正在准备中。当前显示英语简介。
Review HTML tables so screen reader users can understand how headers and data relate. Check header markup, table descriptions, and merged cells, then identify specific fixes and ways to verify them.
中文简介正在准备中。当前显示英语简介。