chromedevtools--chrome-devtools-mcp
Jack Franklin
e8fb30c1bf
This PR tidies up the code around performance parsing and what we respond with from our tools. It introduces the ability to have no Insights from a trace (relatively rare, but can happen), and also adds more information to the output in the event that something went wrong. Previously we just logged errors, but if we respond with them here that will also help users report issues and increase the chances that we can debug them.
96 行
5.1 KiB
Plaintext
96 行
5.1 KiB
Plaintext
exports[`performance > performance_analyze_insight > returns the information on the insight 1`] = `
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## Insight Title: LCP breakdown
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## Insight Summary:
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This insight is used to analyze the time spent that contributed to the final LCP time and identify which of the 4 phases (or 2 if there was no LCP resource) are contributing most to the delay in rendering the LCP element.
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## Detailed analysis:
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The Largest Contentful Paint (LCP) time for this navigation was 129 ms.
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The LCP element is an image fetched from \`https://web-dev.imgix.net/image/kheDArv5csY6rvQUJDbWRscckLr1/4i7JstVZvgTFk9dxCe4a.svg\`.
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## LCP resource network request: https://web-dev.imgix.net/image/kheDArv5csY6rvQUJDbWRscckLr1/4i7JstVZvgTFk9dxCe4a.svg
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Timings:
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- Queued at: 41 ms
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- Request sent at: 47 ms
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- Download complete at: 56 ms
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- Main thread processing completed at: 58 ms
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Durations:
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- Download time: 0.3 ms
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- Main thread processing time: 2 ms
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- Total duration: 17 ms
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Redirects: no redirects
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Status code: 200
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MIME Type: image/svg+xml
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Protocol: unknown
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Priority: VeryHigh
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Render blocking: No
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From a service worker: No
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Initiators (root request to the request that directly loaded this one): none
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We can break this time down into the 4 phases that combine to make the LCP time:
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- Time to first byte: 8 ms (6.1% of total LCP time)
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- Resource load delay: 33 ms (25.7% of total LCP time)
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- Resource load duration: 15 ms (11.4% of total LCP time)
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- Element render delay: 73 ms (56.8% of total LCP time)
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## Estimated savings: none
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## External resources:
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- https://web.dev/articles/lcp
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- https://web.dev/articles/optimize-lcp
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`;
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exports[`performance > performance_stop_trace > returns an error message if parsing the trace buffer fails 1`] = `
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The performance trace has been stopped.
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There was an unexpected error parsing the trace:
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No buffer was provided.
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`;
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exports[`performance > performance_stop_trace > returns the high level summary of the performance trace 1`] = `
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The performance trace has been stopped.
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Here is a high level summary of the trace and the Insights that were found:
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URL: https://web.dev/
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Bounds: {min: 122410994891, max: 122416385853}
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CPU throttling: none
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Network throttling: none
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Metrics (lab / observed):
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- LCP: 129 ms, event: (eventKey: r-6063, ts: 122411126100)
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- LCP breakdown:
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- TTFB: 8 ms, bounds: {min: 122410996889, max: 122411004828}
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- Load delay: 33 ms, bounds: {min: 122411004828, max: 122411037986}
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- Load duration: 15 ms, bounds: {min: 122411037986, max: 122411052690}
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- Render delay: 73 ms, bounds: {min: 122411052690, max: 122411126100}
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- CLS: 0.00
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Metrics (field / real users): n/a – no data for this page in CrUX
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Available insights:
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- insight name: LCPBreakdown
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description: Each [subpart has specific improvement strategies](https://web.dev/articles/optimize-lcp#lcp-breakdown). Ideally, most of the LCP time should be spent on loading the resources, not within delays.
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relevant trace bounds: {min: 122410996889, max: 122411126100}
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example question: Help me optimize my LCP score
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example question: Which LCP phase was most problematic?
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example question: What can I do to reduce the LCP time for this page load?
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- insight name: LCPDiscovery
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description: Optimize LCP by making the LCP image [discoverable](https://web.dev/articles/optimize-lcp#1_eliminate_resource_load_delay) from the HTML immediately, and [avoiding lazy-loading](https://web.dev/articles/lcp-lazy-loading)
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relevant trace bounds: {min: 122411004828, max: 122411055039}
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example question: Suggest fixes to reduce my LCP
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example question: What can I do to reduce my LCP discovery time?
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example question: Why is LCP discovery time important?
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- insight name: RenderBlocking
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description: Requests are blocking the page's initial render, which may delay LCP. [Deferring or inlining](https://web.dev/learn/performance/understanding-the-critical-path#render-blocking_resources) can move these network requests out of the critical path.
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relevant trace bounds: {min: 122411037528, max: 122411053852}
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example question: Show me the most impactful render blocking requests that I should focus on
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example question: How can I reduce the number of render blocking requests?
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- insight name: DocumentLatency
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description: Your first network request is the most important. Reduce its latency by avoiding redirects, ensuring a fast server response, and enabling text compression.
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relevant trace bounds: {min: 122410998910, max: 122411043781}
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estimated metric savings: FCP 0 ms, LCP 0 ms
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estimated wasted bytes: 77.1 kB
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example question: How do I decrease the initial loading time of my page?
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example question: Did anything slow down the request for this document?
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- insight name: ThirdParties
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description: 3rd party code can significantly impact load performance. [Reduce and defer loading of 3rd party code](https://web.dev/articles/optimizing-content-efficiency-loading-third-party-javascript/) to prioritize your page's content.
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relevant trace bounds: {min: 122411037881, max: 122416229595}
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example question: Which third parties are having the largest impact on my page performance?
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`;
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