webperf

1# WebPerf Snippets Toolkit
2 
3A collection of 57 JavaScript snippets for measuring and debugging web performance in Chrome DevTools. Each snippet runs in the page and returns a structured result object.
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5## Quick Reference
6 
7| Skill | Snippets | Trigger phrases |
8|-------|----------|-----------------|
9| webperf-core-web-vitals | 7 | "debug LCP", "slow LCP", "CLS", "layout shifts", "INP", "interaction latency", "responsiveness" |
10| webperf-loading | 35 | "TTFB", "slow server", "FCP", "render blocking", "font loading", "script loading", "resource hints", "service worker" |
11| webperf-interaction | 10 | "jank", "scroll performance", "long tasks", "animation frames", "INP debug" |
12| webperf-media | 4 | "image audit", "lazy loading", "image optimization", "video audit" |
13| webperf-resources | 1 | "network quality", "bandwidth", "connection type", "save-data" |
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15## Workflow
16 
171. Identify the relevant skill based on the user's question (see Quick Reference above)
182. Load the skill's SKILL.md to see available snippets and thresholds
193. Execute with Chrome DevTools MCP:
20   - `mcp__chrome-devtools__navigate_page` → navigate to target URL
21   - `mcp__chrome-devtools__evaluate_script` with `sourcePath` (the absolute path of the script) and `format: "script"` → run the snippet and read the returned object, which is the result (the scripts have no console output)
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