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feat: web vitals 3000 #1401

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merged 8 commits into from
Sep 9, 2024
Merged

feat: web vitals 3000 #1401

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2e8e3a5
take a step
pauldambra Sep 6, 2024
a8e5490
fiddling
pauldambra Sep 6, 2024
3c1325b
more
pauldambra Sep 6, 2024
8c590c3
add INP attribution
pauldambra Sep 6, 2024
3bca8b2
fix
pauldambra Sep 6, 2024
8043fa8
fix
pauldambra Sep 7, 2024
6dced38
fix
pauldambra Sep 7, 2024
c4d5016
remove sampling
pauldambra Sep 7, 2024
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273 changes: 178 additions & 95 deletions src/__tests__/extensions/web-vitals.test.ts
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Original file line number Diff line number Diff line change
@@ -1,7 +1,7 @@
import { createPosthogInstance } from '../helpers/posthog-instance'
import { uuidv7 } from '../../uuidv7'
import { PostHog } from '../../posthog-core'
import { DecideResponse } from '../../types'
import { DecideResponse, SupportedWebVitalsMetrics } from '../../types'
import { assignableWindow } from '../../utils/globals'
import { FLUSH_TO_CAPTURE_TIMEOUT_MILLISECONDS, FIFTEEN_MINUTES_IN_MILLIS } from '../../extensions/web-vitals'

Expand All @@ -17,16 +17,6 @@ describe('web vitals', () => {
let onINPCallback: ((metric: Record<string, any>) => void) | undefined = undefined
const loadScriptMock = jest.fn()

const randomlyAddAMetric = (
metricName: string = 'metric',
metricValue: number = 600.1,
metricProperties: Record<string, any> = {}
) => {
const callbacks = [onLCPCallback, onCLSCallback, onFCPCallback, onINPCallback]
const randomIndex = Math.floor(Math.random() * callbacks.length)
callbacks[randomIndex]?.({ name: metricName, value: metricValue, ...metricProperties })
}

const emitAllMetrics = () => {
onLCPCallback?.({ name: 'LCP', value: 123.45, extra: 'property' })
onCLSCallback?.({ name: 'CLS', value: 123.45, extra: 'property' })
Expand All @@ -44,112 +34,154 @@ describe('web vitals', () => {
extra: 'property',
})

describe('the behaviour', () => {
beforeEach(async () => {
posthog = await createPosthogInstance(uuidv7(), {
_onCapture: onCapture,
capture_performance: { web_vitals: true },
// sometimes pageviews sneak in and make asserting on mock capture tricky
capture_pageview: false,
})
describe.each([
[
undefined,
['CLS', 'FCP', 'INP', 'LCP'] as SupportedWebVitalsMetrics[],
{
$web_vitals_LCP_event: expectedEmittedWebVitals('LCP'),
$web_vitals_LCP_value: 123.45,
$web_vitals_CLS_event: expectedEmittedWebVitals('CLS'),
$web_vitals_CLS_value: 123.45,
$web_vitals_FCP_event: expectedEmittedWebVitals('FCP'),
$web_vitals_FCP_value: 123.45,
$web_vitals_INP_event: expectedEmittedWebVitals('INP'),
$web_vitals_INP_value: 123.45,
},
],
[
['CLS', 'FCP', 'INP', 'LCP'] as SupportedWebVitalsMetrics[],
['CLS', 'FCP', 'INP', 'LCP'] as SupportedWebVitalsMetrics[],
{
$web_vitals_LCP_event: expectedEmittedWebVitals('LCP'),
$web_vitals_LCP_value: 123.45,
$web_vitals_CLS_event: expectedEmittedWebVitals('CLS'),
$web_vitals_CLS_value: 123.45,
$web_vitals_FCP_event: expectedEmittedWebVitals('FCP'),
$web_vitals_FCP_value: 123.45,
$web_vitals_INP_event: expectedEmittedWebVitals('INP'),
$web_vitals_INP_value: 123.45,
},
],
[
['CLS', 'FCP'] as SupportedWebVitalsMetrics[],
['CLS', 'FCP'] as SupportedWebVitalsMetrics[],
{
$web_vitals_CLS_event: expectedEmittedWebVitals('CLS'),
$web_vitals_CLS_value: 123.45,
$web_vitals_FCP_event: expectedEmittedWebVitals('FCP'),
$web_vitals_FCP_value: 123.45,
},
],
])(
'the behaviour when client config is %s',
(
clientConfig: SupportedWebVitalsMetrics[] | undefined,
expectedAllowedMetrics: SupportedWebVitalsMetrics[],
expectedProperties: Record<string, any>
) => {
beforeEach(async () => {
onCapture.mockClear()
posthog = await createPosthogInstance(uuidv7(), {
_onCapture: onCapture,
capture_performance: { web_vitals: true, web_vitals_metrics: clientConfig },
// sometimes pageviews sneak in and make asserting on mock capture tricky
capture_pageview: false,
})

loadScriptMock.mockImplementation((_path, callback) => {
// we need a set of fake web vitals handlers, so we can manually trigger the events
assignableWindow.postHogWebVitalsCallbacks = {
onLCP: (cb: any) => {
onLCPCallback = cb
},
onCLS: (cb: any) => {
onCLSCallback = cb
},
onFCP: (cb: any) => {
onFCPCallback = cb
},
onINP: (cb: any) => {
onINPCallback = cb
},
}
callback()
loadScriptMock.mockImplementation((_path, callback) => {
// we need a set of fake web vitals handlers, so we can manually trigger the events
assignableWindow.__PosthogExtensions__ = {}
assignableWindow.__PosthogExtensions__.postHogWebVitalsCallbacks = {
onLCP: (cb: any) => {
onLCPCallback = cb
},
onCLS: (cb: any) => {
onCLSCallback = cb
},
onFCP: (cb: any) => {
onFCPCallback = cb
},
onINP: (cb: any) => {
onINPCallback = cb
},
}
callback()
})

posthog.requestRouter.loadScript = loadScriptMock

// need to force this to get the web vitals script loaded
posthog.webVitalsAutocapture!.afterDecideResponse({
capturePerformance: { web_vitals: true },
} as unknown as DecideResponse)

expect(posthog.webVitalsAutocapture.allowedMetrics).toEqual(expectedAllowedMetrics)
})

posthog.requestRouter.loadScript = loadScriptMock
it('should emit when all allowed metrics are captured', async () => {
emitAllMetrics()

// need to force this to get the web vitals script loaded
posthog.webVitalsAutocapture!.afterDecideResponse({
capturePerformance: { web_vitals: true },
} as unknown as DecideResponse)
})
expect(onCapture).toBeCalledTimes(1)

it('should emit when all 4 metrics are captured', async () => {
emitAllMetrics()

expect(onCapture).toBeCalledTimes(1)

expect(onCapture.mock.lastCall).toMatchObject([
'$web_vitals',
{
event: '$web_vitals',
properties: {
$web_vitals_LCP_event: expectedEmittedWebVitals('LCP'),
$web_vitals_LCP_value: 123.45,
$web_vitals_CLS_event: expectedEmittedWebVitals('CLS'),
$web_vitals_CLS_value: 123.45,
$web_vitals_FCP_event: expectedEmittedWebVitals('FCP'),
$web_vitals_FCP_value: 123.45,
$web_vitals_INP_event: expectedEmittedWebVitals('INP'),
$web_vitals_INP_value: 123.45,
expect(onCapture.mock.lastCall).toMatchObject([
'$web_vitals',
{
event: '$web_vitals',
properties: expectedProperties,
},
},
])
})
])
})

it('should emit after 8 seconds even when only 1 to 3 metrics captured', async () => {
randomlyAddAMetric('LCP', 123.45, { extra: 'property' })
it('should emit after 8 seconds even when only 1 to 3 metrics captured', async () => {
onCLSCallback?.({ name: 'CLS', value: 123.45, extra: 'property' })

expect(onCapture).toBeCalledTimes(0)
expect(onCapture).toBeCalledTimes(0)

jest.advanceTimersByTime(FLUSH_TO_CAPTURE_TIMEOUT_MILLISECONDS + 1)
jest.advanceTimersByTime(FLUSH_TO_CAPTURE_TIMEOUT_MILLISECONDS + 1)

// for some reason advancing the timer emits a $pageview event as well 🤷
// expect(onCapture).toBeCalledTimes(2)
expect(onCapture.mock.lastCall).toMatchObject([
'$web_vitals',
{
event: '$web_vitals',
properties: {
$web_vitals_LCP_event: expectedEmittedWebVitals('LCP'),
$web_vitals_LCP_value: 123.45,
// for some reason advancing the timer emits a $pageview event as well 🤷
// expect(onCapture).toBeCalledTimes(2)
expect(onCapture.mock.lastCall).toMatchObject([
'$web_vitals',
{
event: '$web_vitals',
properties: {
$web_vitals_CLS_event: expectedEmittedWebVitals('CLS'),
$web_vitals_CLS_value: 123.45,
},
},
},
])
})
])
})

it('should ignore a ridiculous value', async () => {
randomlyAddAMetric('LCP', FIFTEEN_MINUTES_IN_MILLIS, { extra: 'property' })
it('should ignore a ridiculous value', async () => {
onCLSCallback?.({ name: 'CLS', value: FIFTEEN_MINUTES_IN_MILLIS, extra: 'property' })

expect(onCapture).toBeCalledTimes(0)
expect(onCapture).toBeCalledTimes(0)

jest.advanceTimersByTime(FLUSH_TO_CAPTURE_TIMEOUT_MILLISECONDS + 1)
jest.advanceTimersByTime(FLUSH_TO_CAPTURE_TIMEOUT_MILLISECONDS + 1)

expect(onCapture).toBeCalledTimes(0)
})
expect(onCapture.mock.calls).toEqual([])
})

it('can be configured not to ignore a ridiculous value', async () => {
posthog.config.capture_performance = { __web_vitals_max_value: 0 }
randomlyAddAMetric('LCP', FIFTEEN_MINUTES_IN_MILLIS, { extra: 'property' })
it('can be configured not to ignore a ridiculous value', async () => {
posthog.config.capture_performance = { __web_vitals_max_value: 0 }
onCLSCallback?.({ name: 'CLS', value: FIFTEEN_MINUTES_IN_MILLIS, extra: 'property' })

expect(onCapture).toBeCalledTimes(0)
expect(onCapture).toBeCalledTimes(0)

jest.advanceTimersByTime(FLUSH_TO_CAPTURE_TIMEOUT_MILLISECONDS + 1)
jest.advanceTimersByTime(FLUSH_TO_CAPTURE_TIMEOUT_MILLISECONDS + 1)

expect(onCapture).toBeCalledTimes(1)
})
})
expect(onCapture).toBeCalledTimes(1)
})
}
)

describe('afterDecideResponse()', () => {
beforeEach(async () => {
// we need a set of fake web vitals handlers so we can manually trigger the events
assignableWindow.postHogWebVitalsCallbacks = {
// we need a set of fake web vitals handlers, so we can manually trigger the events
assignableWindow.__PosthogExtensions__ = {}
assignableWindow.__PosthogExtensions__.postHogWebVitalsCallbacks = {
onLCP: (cb: any) => {
onLCPCallback = cb
},
Expand Down Expand Up @@ -202,4 +234,55 @@ describe('web vitals', () => {
}
)
})

describe.each(['client', 'server'])('sampling', (configSource) => {
describe.each([
[0, 0, 0],
[1, 100, 100],
[0.5, 40, 60],
])(`with sample rate of %f`, (sampleRate: number, min: number, max: number) => {
beforeEach(async () => {
// we need a set of fake web vitals handlers, so we can manually trigger the events
assignableWindow.__PosthogExtensions__ = {}
assignableWindow.__PosthogExtensions__.postHogWebVitalsCallbacks = {
onLCP: (cb: any) => {
onLCPCallback = cb
},
onCLS: (cb: any) => {
onCLSCallback = cb
},
onFCP: (cb: any) => {
onFCPCallback = cb
},
onINP: (cb: any) => {
onINPCallback = cb
},
}
})

it(`with config from ${configSource} captures roughly half the time when sample rate is 0.5`, async () => {
posthog = await createPosthogInstance(uuidv7(), {
_onCapture: onCapture,
capture_performance: {
web_vitals: true,
web_vitals_sample_rate: configSource === 'client' ? sampleRate : undefined,
},
})

posthog.webVitalsAutocapture!.afterDecideResponse({
capturePerformance: {
web_vitals: true,
web_vitals_sample_rate: configSource === 'server' ? sampleRate : undefined,
},
} as DecideResponse)

for (let i = 0; i < 100; i++) {
emitAllMetrics()
}

expect(onCapture.mock.calls.length).toBeGreaterThanOrEqual(min)
expect(onCapture.mock.calls.length).toBeLessThanOrEqual(max)
})
})
})
})
2 changes: 2 additions & 0 deletions src/constants.ts
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Original file line number Diff line number Diff line change
Expand Up @@ -15,6 +15,8 @@ export const HEATMAPS_ENABLED_SERVER_SIDE = '$heatmaps_enabled_server_side'
export const EXCEPTION_CAPTURE_ENABLED_SERVER_SIDE = '$exception_capture_enabled_server_side'
export const EXCEPTION_CAPTURE_ENDPOINT_SUFFIX = '$exception_capture_endpoint_suffix'
export const WEB_VITALS_ENABLED_SERVER_SIDE = '$web_vitals_enabled_server_side'
export const WEB_VITALS_SAMPLE_RATE = '$web_vitals_sample_rate'
export const WEB_VITALS_ALLOWED_METRICS = '$web_vitals_allowed_metrics'
export const SESSION_RECORDING_ENABLED_SERVER_SIDE = '$session_recording_enabled_server_side'
export const CONSOLE_LOG_RECORDING_ENABLED_SERVER_SIDE = '$console_log_recording_enabled_server_side'
export const SESSION_RECORDING_NETWORK_PAYLOAD_CAPTURE = '$session_recording_network_payload_capture'
Expand Down
8 changes: 4 additions & 4 deletions src/entrypoints/web-vitals.ts
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Original file line number Diff line number Diff line change
@@ -1,15 +1,15 @@
import { onLCP, onINP, onCLS, onFCP } from 'web-vitals'
import { onLCP, onCLS, onFCP } from 'web-vitals'
import { onINP } from 'web-vitals/attribution'
import { assignableWindow } from '../utils/globals'

// TODO export types here as well?

const postHogWebVitalsCallbacks = {
onLCP,
onCLS,
onFCP,
onINP,
}

assignableWindow.postHogWebVitalsCallbacks = postHogWebVitalsCallbacks
assignableWindow.__PosthogExtensions__ = assignableWindow.__PosthogExtensions__ || {}
assignableWindow.__POSTHOG_EXTENSIONS__postHogWebVitalsCallbacks = postHogWebVitalsCallbacks
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every time we add random things onto the window an angel dies (probably)

so I'm slowly moving things onto a single global object on window

this will mean we can start to type that object and have fewer (window as any) flying around the place


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export default postHogWebVitalsCallbacks
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