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Add Time to First Byte collection #5

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17 changes: 17 additions & 0 deletions documents/adr/001-web-vitals.md
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@@ -0,0 +1,17 @@
# 001-web-vitals

## Status

Approved

## Context

There is good adoption of synthetic performance testing tools, particularly Google Lighthouse and [Page Speed Insights](https://pagespeed.web.dev). There are not as many widely deployed tools to anonymously collect field measurements of page speed performance from real users in a way that adequately captures their experience when using federal web properties.

## Decision

Google Analytics through the Digital Analytics Program within the federal government already has good adoption within the federal government. The `web-vitals.js` library from Google was selected as a way to instrument a website or application with performance collection. This library was chosen for its stability, as well as its completeness, as it is the basis of many commercial offerings (e.g. DataDog, Sentry) and its wide deployment through the Chrome Devtools Performance Panel.

## Consequences

This proposes an optional add-on for teams to be able to add and collect metrics on what a real user experiences as it relates to the universal performance indicators known as Core Web Vitals.
63 changes: 0 additions & 63 deletions package-lock.json
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18 changes: 16 additions & 2 deletions src/format-event-data.ts
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Expand Up @@ -3,14 +3,16 @@ import type {
FCPAttribution,
INPAttribution,
LCPAttribution,
TTFBAttribution,
} from 'web-vitals';

export type WebVitalsName = 'CLS' | 'FCP' | 'INP' | 'LCP';
export type WebVitalsName = 'CLS' | 'FCP' | 'INP' | 'LCP' | 'TTFB';
export type WebVitalsAttribution =
| CLSAttribution
| FCPAttribution
| INPAttribution
| LCPAttribution;
| LCPAttribution
| TTFBAttribution;

export const formatEventData = (
name: WebVitalsName,
Expand Down Expand Up @@ -69,6 +71,18 @@ export const formatEventData = (
debug_target: (attribution as LCPAttribution).element || '(not set)',
};
}
if (name === 'TTFB') {
return {
debug_waiting_duration: (attribution as TTFBAttribution)
.waitingDuration,
debug_dns_duration: (attribution as TTFBAttribution).dnsDuration,
debug_connection_duration: (attribution as TTFBAttribution)
.connectionDuration,
debug_cache_duration: (attribution as TTFBAttribution).cacheDuration,
debug_request_duration: (attribution as TTFBAttribution)
.requestDuration,
};
}
}
// Return default/empty params in case there is no attribution.
return {
Expand Down
3 changes: 2 additions & 1 deletion src/index.ts
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@@ -1,11 +1,12 @@
import { onCLS, onINP, onFCP, onLCP } from './web-vitals.js';
import { onCLS, onINP, onFCP, onLCP, onTTFB } from './web-vitals.js';
import { sendToAnalytics } from './send-to-analytics.js';

const initWebVitalsEvents = () => {
onCLS(sendToAnalytics);
onFCP(sendToAnalytics);
onINP(sendToAnalytics);
onLCP(sendToAnalytics);
onTTFB(sendToAnalytics);
};

if (typeof window !== 'undefined' && 'gas4' in window) {
Expand Down
4 changes: 3 additions & 1 deletion src/send-to-analytics.ts
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Expand Up @@ -3,6 +3,7 @@ import type {
FCPMetricWithAttribution,
INPMetricWithAttribution,
LCPMetricWithAttribution,
TTFBMetricWithAttribution,
} from 'web-vitals';

import { formatEventData, type WebVitalsName } from './format-event-data.js';
Expand All @@ -11,7 +12,8 @@ export type WebVitalsWithAttribution =
| CLSMetricWithAttribution
| FCPMetricWithAttribution
| INPMetricWithAttribution
| LCPMetricWithAttribution;
| LCPMetricWithAttribution
| TTFBMetricWithAttribution;

declare const gas4: any;

Expand Down
4 changes: 2 additions & 2 deletions src/web-vitals.ts
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@@ -1,3 +1,3 @@
import { onCLS, onINP, onFCP, onLCP } from 'web-vitals/attribution';
import { onCLS, onINP, onFCP, onLCP, onTTFB } from 'web-vitals/attribution';

export { onCLS, onINP, onFCP, onLCP };
export { onCLS, onINP, onFCP, onLCP, onTTFB };
111 changes: 111 additions & 0 deletions test/unit/format-event-data.test.ts
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Expand Up @@ -84,6 +84,27 @@ describe('formatEventData', () => {
});
});

it('should format TTFB data correctly', () => {
const attribution = {
waitingDuration: 0,
cacheDuration: 0,
dnsDuration: 0,
connectionDuration: 2015,
requestDuration: 47,
};

// @ts-ignore
const result = formatEventData('TTFB', attribution);

expect(result).toEqual({
debug_cache_duration: attribution.cacheDuration,
debug_connection_duration: attribution.connectionDuration,
debug_dns_duration: attribution.dnsDuration,
debug_request_duration: attribution.requestDuration,
debug_waiting_duration: attribution.waitingDuration,
});
});

it('should return default/empty params if no attribution data is provided', () => {
// @ts-ignore
const result = formatEventData('unknown', null);
Expand Down Expand Up @@ -453,3 +474,93 @@ describe('formatEventData', () => {
// }
// }
// }

// {
// "name": "TTFB",
// "value": 2062,
// "rating": "poor",
// "delta": 2062,
// "entries": [
// {
// "name": "http://localhost:8000/demo/",
// "entryType": "navigation",
// "startTime": 0,
// "duration": 4181,
// "initiatorType": "navigation",
// "nextHopProtocol": "http/1.1",
// "workerStart": 0,
// "redirectStart": 0,
// "redirectEnd": 0,
// "fetchStart": -21,
// "domainLookupStart": -21,
// "domainLookupEnd": -21,
// "connectStart": -21,
// "connectEnd": 2015,
// "secureConnectionStart": 0,
// "requestStart": 2016,
// "responseStart": 2062,
// "responseEnd": 2062,
// "transferSize": 4277,
// "encodedBodySize": 3977,
// "decodedBodySize": 3977,
// "responseStatus": 200,
// "contentType": "text/html",
// "serverTiming": [],
// "unloadEventStart": 0,
// "unloadEventEnd": 0,
// "domInteractive": 2126,
// "domContentLoadedEventStart": 2199,
// "domContentLoadedEventEnd": 2200,
// "domComplete": 4180,
// "loadEventStart": 4180,
// "loadEventEnd": 4181,
// "type": "navigate",
// "redirectCount": 0
// }
// ],
// "id": "v4-1732826806920-8943990242578",
// "navigationType": "navigate",
// "attribution": {
// "waitingDuration": 0,
// "cacheDuration": 0,
// "dnsDuration": 0,
// "connectionDuration": 2015,
// "requestDuration": 47,
// "navigationEntry": {
// "name": "http://localhost:8000/demo/",
// "entryType": "navigation",
// "startTime": 0,
// "duration": 4181,
// "initiatorType": "navigation",
// "nextHopProtocol": "http/1.1",
// "workerStart": 0,
// "redirectStart": 0,
// "redirectEnd": 0,
// "fetchStart": -21,
// "domainLookupStart": -21,
// "domainLookupEnd": -21,
// "connectStart": -21,
// "connectEnd": 2015,
// "secureConnectionStart": 0,
// "requestStart": 2016,
// "responseStart": 2062,
// "responseEnd": 2062,
// "transferSize": 4277,
// "encodedBodySize": 3977,
// "decodedBodySize": 3977,
// "responseStatus": 200,
// "contentType": "text/html",
// "serverTiming": [],
// "unloadEventStart": 0,
// "unloadEventEnd": 0,
// "domInteractive": 2126,
// "domContentLoadedEventStart": 2199,
// "domContentLoadedEventEnd": 2200,
// "domComplete": 4180,
// "loadEventStart": 4180,
// "loadEventEnd": 4181,
// "type": "navigate",
// "redirectCount": 0
// }
// }
// }