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feat(web-vitals): Capture information about the LCP element culprit #3427

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Merged
merged 5 commits into from
Apr 22, 2021
Merged

feat(web-vitals): Capture information about the LCP element culprit #3427

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ea1c3bb
feat(web-vitals): Capture information about the LCP element culprit
dashed Apr 20, 2021
5f42677
update toJSON() type
dashed Apr 21, 2021
fb850b3
Merge branch 'master' into tag-lcp-elements
dashed Apr 22, 2021
c513a29
trim url to the first 200 characters
dashed Apr 22, 2021
875264e
Merge branch 'master' into tag-lcp-elements
dashed Apr 22, 2021
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26 changes: 24 additions & 2 deletions packages/tracing/src/browser/metrics.ts
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Original file line number Diff line number Diff line change
@@ -1,14 +1,14 @@
/* eslint-disable max-lines */
/* eslint-disable @typescript-eslint/no-explicit-any */
import { Measurements, SpanContext } from '@sentry/types';
import { browserPerformanceTimeOrigin, getGlobalObject, logger } from '@sentry/utils';
import { browserPerformanceTimeOrigin, getGlobalObject, htmlTreeAsString, logger } from '@sentry/utils';

import { Span } from '../span';
import { Transaction } from '../transaction';
import { msToSec } from '../utils';
import { getCLS } from './web-vitals/getCLS';
import { getFID } from './web-vitals/getFID';
import { getLCP } from './web-vitals/getLCP';
import { getLCP, LargestContentfulPaint } from './web-vitals/getLCP';
import { getTTFB } from './web-vitals/getTTFB';
import { getFirstHidden } from './web-vitals/lib/getFirstHidden';
import { NavigatorDeviceMemory, NavigatorNetworkInformation } from './web-vitals/types';
Expand All @@ -20,6 +20,7 @@ export class MetricsInstrumentation {
private _measurements: Measurements = {};

private _performanceCursor: number = 0;
private _lcpEntry: LargestContentfulPaint | undefined;

public constructor() {
if (global && global.performance) {
Expand Down Expand Up @@ -170,6 +171,26 @@ export class MetricsInstrumentation {
}

transaction.setMeasurements(this._measurements);

if (this._lcpEntry) {
logger.log('[Measurements] Adding LCP Data');
// Capture Properties of the LCP element that contributes to the LCP.

if (this._lcpEntry.element) {
transaction.setTag('lcp.element', htmlTreeAsString(this._lcpEntry.element));
}

if (this._lcpEntry.id) {
transaction.setTag('lcp.id', this._lcpEntry.id);
}

if (this._lcpEntry.url) {
// Trim URL to the first 200 characters.
transaction.setTag('lcp.url', this._lcpEntry.url.trim().slice(0, 200));
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@dashed do you think it will be important to disambiguate in Sentry when the attribute was truncated or not?

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@k-fish any thoughts on this?

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The only way to clearly disambiguate it would be to set another tag when it was truncated, I feel like this is overkill considering we're not sure this is even necessary. I'd wait on adding any additional data until we see a clear case for it in the product.

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@dashed dashed Apr 22, 2021 •
edited
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@rhcarvalho @k-fish I'll merge this in as is. Once we surface this on the product on the segment explorer, it'll be obvious if there's a need to disambiguate it. And if there is, we can follow up with another PR.

}

transaction.setTag('lcp.size', this._lcpEntry.size);
}
}
}

Expand Down Expand Up @@ -241,6 +262,7 @@ export class MetricsInstrumentation {
logger.log('[Measurements] Adding LCP');
this._measurements['lcp'] = { value: metric.value };
this._measurements['mark.lcp'] = { value: timeOrigin + startTime };
this._lcpEntry = entry as LargestContentfulPaint;
});
}

Expand Down
11 changes: 11 additions & 0 deletions packages/tracing/src/browser/web-vitals/getLCP.ts
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Expand Up @@ -22,6 +22,17 @@ import { onHidden } from './lib/onHidden';
import { whenInput } from './lib/whenInput';
import { ReportHandler } from './types';

// https://wicg.github.io/largest-contentful-paint/#sec-largest-contentful-paint-interface
export interface LargestContentfulPaint extends PerformanceEntry {
renderTime: DOMHighResTimeStamp;
loadTime: DOMHighResTimeStamp;
size: number;
id: string;
url: string;
element?: Element;
toJSON(): Record<string, string>;
}

export const getLCP = (onReport: ReportHandler, reportAllChanges = false): void => {
const metric = initMetric('LCP');
const firstHidden = getFirstHidden();
Expand Down