Audit website images for excessive file sizes, unnecessary metadata, and loading issues. Apply format-specific compression and cleanup, then compare file sizes before and after changes to show the resulting reduction in image data.
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Use when reviewing image assets, markup, and CDN or build transforms related to Optimise images for faster loading. 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。
Unoptimised images are the most prevalent cause of page bloat. A DSLR-quality JPEG with EXIF data can be 8MB; the same image optimised for web delivery is under 200KB with no visible quality difference. Lighthouse's 'Efficiently encode images' audit reports potential savings that, when fixed, directly improve LCP and reduce bandwidth costs.
progressive: true (mozjpeg); PNG: run pngquant at quality 65-80Audit all image assets in this project for optimisation issues: 1) Run Lighthouse and check the 'Efficiently encode images' audit—it flags images that could be reduced by 4KB or more. 2) Check if JPEG images use progressive encoding (better perceived performance). 3) Check if images retain EXIF/IPTC metadata (adds unnecessary bytes). 4) Check if PNG images could be quantised (pngquant) for smaller files. 5) Check if SVG files contain unnecessary editor metadata, comments, or redundant attributes. Report each image with its current size and estimated savings.
For each unoptimised image: 1) JPEG: re-encode with mozjpeg at quality 80 with progressive=true. 2) PNG: run pngquant at quality 65-80 for lossy compression, or oxipng for lossless. 3) WebP: encode at quality 80. 4) AVIF: encode at quality 60 with effort 6. 5) SVG: run through SVGO to remove editor metadata, comments, and redundant attributes. 6) Strip EXIF metadata from all JPEG/WebP images. For each image, show the before/after file size and percentage reduction.
Explain what image optimisation means technically. JPEG compression works by converting pixel data to frequency components (DCT) and quantising the high-frequency data—quality settings control how aggressively this quantisation occurs. PNG uses lossless DEFLATE compression, but colour quantisation (pngquant) can massively reduce file size with minimal visible change. EXIF metadata (GPS, camera model, timestamps) adds kilobytes to images with no benefit for web users. Progressive JPEG encoding allows the browser to show a low-resolution version immediately while the full image loads, improving perceived performance.
Review image assets, markup, and delivery configuration related to Optimise images for faster loading. 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/optimized
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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.
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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.
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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.
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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。