[RUM-14619] Add addViewLoadingTime() public API by MaelNamNam · Pull Request #4180 · DataDog/browser-sdk

MaelNamNam · 2026-02-13T10:27:07Z

Motivation

Allow developers to manually report view loading time for complex async patterns (SPAs with deferred fetching, skeleton screens) where auto-detection is inaccurate.

Brings Browser SDK to parity with iOS/Android SDKs.

Changes

New public API: DD_RUM.addViewLoadingTime(options?)

Loading time = elapsed since current view start
First call suppresses auto-detected loading time
First-call-wins by default; { overwrite: true } to replace
Pre-start buffering supported (calls before init() are drained with preserved timestamps)
Telemetry: no_view, no_active_view, overwritten (aligned with mobile schema)

Upstream dep: rum-events-format#352 — once merged, the manual type in telemetryEvent.types.ts can be replaced by the generated one.

Test instructions

yarn test:unit --spec packages/rum-core/src/domain/view/trackViews.spec.ts
yarn test:unit --spec packages/rum-core/src/boot/rumPublicApi.spec.ts
yarn test:unit --spec packages/rum-core/src/boot/preStartRum.spec.ts
yarn test:e2e:init && yarn test:e2e -g "manual loading time"

Checklist

Tested locally
Tested on staging
Added unit tests for this change.
Added e2e/integration tests for this change.
Updated documentation and/or relevant AGENTS.md file

github-actions · 2026-02-13T10:27:22Z

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cit-pr-commenter-54b7da · 2026-02-13T10:28:08Z

Bundles Sizes Evolution

📦 Bundle Name	Base Size	Local Size	𝚫	𝚫%	Status
Rum	169.43 KiB	170.37 KiB	+962 B	+0.55%	✅
Rum Profiler	4.29 KiB	4.29 KiB	0 B	0.00%	✅
Rum Recorder	24.54 KiB	24.54 KiB	0 B	0.00%	✅
Logs	56.72 KiB	56.77 KiB	+48 B	+0.08%	✅
Flagging	944 B	944 B	0 B	0.00%	✅
Rum Slim	126.26 KiB	127.16 KiB	+918 B	+0.71%	✅
Worker	23.63 KiB	23.63 KiB	0 B	0.00%	✅

🚀 CPU Performance

Action Name	Base CPU Time (ms)	Local CPU Time (ms)	𝚫%
RUM - add global context	0.0045	0.0096	+113.33%
RUM - add action	0.0142	0.0668	+370.42%
RUM - add error	0.0133	0.0384	+188.72%
RUM - add timing	0.0028	0.0114	+307.14%
RUM - start view	0.0134	0.0443	+230.60%
RUM - start/stop session replay recording	0.0007	0.0024	+242.86%
Logs - log message	0.0155	0.0545	+251.61%

🧠 Memory Performance

Action Name	Base Memory Consumption	Local Memory Consumption	𝚫
RUM - add global context	27.68 KiB	27.11 KiB	-581 B
RUM - add action	51.86 KiB	50.36 KiB	-1.49 KiB
RUM - add timing	26.47 KiB	26.60 KiB	+125 B
RUM - add error	57.53 KiB	56.56 KiB	-991 B
RUM - start/stop session replay recording	25.70 KiB	25.70 KiB	+4 B
RUM - start view	453.18 KiB	467.53 KiB	+14.35 KiB
Logs - log message	47.21 KiB	46.58 KiB	-649 B

🔗 RealWorld

datadog-datadog-prod-us1 · 2026-02-13T10:29:04Z

✅ Tests

🎉 All green!

❄️ No new flaky tests detected
🧪 All tests passed

🎯 Code Coverage (details)
• Patch Coverage: 82.14%
• Overall Coverage: 77.29% (+0.16%)

_{This comment will be updated automatically if new data arrives.

🔗 Commit SHA: 874630d | Docs | Datadog PR Page | Was this helpful? React with 👍/👎 or give us feedback!}

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chatgpt-codex-connector · 2026-02-13T10:32:08Z

packages/rum-core/src/boot/rumPublicApi.ts

+        no_active_view: isResult && 'no_active_view' in result,
+        overwritten: isResult && 'overwritten' in result && result.overwritten !== false,


Default telemetry flags to false for buffered calls

When addViewLoadingTime() is called before init, strategy.addLoadingTime(...) returns undefined, so isResult && ... evaluates to undefined for both no_active_view and overwritten. Those fields are then omitted from the telemetry payload instead of being sent as explicit booleans, which contradicts the AddViewLoadingTime usage schema and makes pre-start telemetry inaccurate. Please coerce these expressions to false when no result is available.

Useful? React with 👍 / 👎.

Add a new public API `DD_RUM.addViewLoadingTime(options?)` that allows developers to manually report when a view has finished loading. - Computes loading time as elapsed time since view start - Suppresses auto-detected loading time on first manual call - First-call-wins by default; `{ overwrite: true }` to replace - Pre-start buffering with preserved call timestamps - Telemetry usage tracking - Gracefully no-ops on ended/expired views - Unit tests + E2E test

packages/rum-core/src/domain/view/trackViews.ts

packages/rum-core/src/domain/view/viewMetrics/trackCommonViewMetrics.ts

thomas-lebeau · 2026-02-13T14:47:03Z

packages/rum-core/src/boot/rumPublicApi.ts

+      addTelemetryUsage({
+        feature: 'addViewLoadingTime',
+        no_view: false,
+        no_active_view: isResult && 'no_active_view' in result,
+        overwritten: isResult && 'overwritten' in result && result.overwritten !== false,
+      })


❓ question: TelemetryUsage is meant to understand which API the customer are using and with which option when available. I don't think we should return run-time analysis like this.

Suggested change

addTelemetryUsage({

feature: 'addViewLoadingTime',

no_view: false,

no_active_view: isResult && 'no_active_view' in result,

overwritten: isResult && 'overwritten' in result && result.overwritten !== false,

})

addTelemetryUsage({

feature: 'addViewLoadingTime',

overwrite

})

Good point. I went a different direction though — I aligned the telemetry with the mobile SDK schema instead, which tracks runtime state (no_view, no_active_view, overwritten). This matches what iOS/Android already report for AddViewLoadingTime. See c25c762.

packages/rum-core/src/boot/rumPublicApi.ts

packages/core/src/domain/telemetry/telemetryEvent.types.ts

thomas-lebeau · 2026-02-13T14:54:49Z

packages/rum-core/src/boot/rumPublicApi.ts

+      const result = strategy.addLoadingTime(callTimestamp, options?.overwrite ?? false)
+
+      // For pre-start buffered calls, result is undefined so we emit best-guess default values.
+      const isResult = result && typeof result === 'object'


💬 suggestion: ‏use Types to prevent runtime assertion

Kept the runtime assertion — it feeds the no_active_view and overwritten telemetry fields that are now aligned with the mobile SDK schema. See c25c762.

…JSDoc link - Remove '(CONTEXT decision)' comment from trackCommonViewMetrics.ts - Remove 'Phase 2 telemetry' comment from trackCommonViewMetrics.ts - Remove broken JSDoc link to non-existent doc page from rumPublicApi.ts

- Refactor addLoadingTime to return void at newView and trackViews layers - Simplify telemetry to user intent, remove runtime assertion - Add unit and E2E tests for manual loading time coverage - Draft RFC for addViewLoadingTime() public API

…xperimental gate - Add SET_VIEW_LOADING_TIME enum member to ExperimentalFeature - Rename addViewLoadingTime to setViewLoadingTime on RumPublicApi interface and implementation - Add experimental feature guard that fires display.warn() when flag is disabled - Preserve telemetry wire format string 'addViewLoadingTime' unchanged - Import display from @datadog/browser-core for warning output

…e and experimental gate - Rename describe block from addViewLoadingTime to setViewLoadingTime - Add mockExperimentalFeatures([SET_VIEW_LOADING_TIME]) to existing working tests - Rename all rumPublicApi.addViewLoadingTime() calls to setViewLoadingTime() - Add no-op test verifying display.warn() fires when experimental flag is disabled - Update E2E tests to use setViewLoadingTime() with enableExperimentalFeatures config

…from browser payload - Mark no_view and no_active_view as optional in AddViewLoadingTime interface with [MANUAL] comments - Remove no_view and no_active_view from addTelemetryUsage call in setViewLoadingTime - Browser never meaningfully sent these mobile-only fields (always false)

…te experimental status in RFC - Rename all public API references from addViewLoadingTime to setViewLoadingTime - Preserve telemetry wire format string 'addViewLoadingTime' (backend contract) - Update Open Questions Q1 from Stable to Experimental with rationale - Add Constraint #7 documenting experimental gate and backend pipeline vision - Update Annex A browser row to Experimental stability - Add v1.2 changelog entry

…in RFC - Replace telemetry block to show only feature + overwritten (no no_view, no no_active_view) - Add three naming surfaces table (public API, wire format, TypeScript interface) - Add Constraint #8 documenting no auto-detection opt-out rationale - Update no_view/no_active_view note to explain browser omission - Update pre-start telemetry cons bullet to remove no_active_view reference

- Create 11-01-SUMMARY.md with execution results - Update STATE.md: Phase 11 complete, all v1.2 phases done, 100% progress - Update ROADMAP.md: Phase 11 plan progress - Mark RFC-01 through RFC-04 requirements complete in REQUIREMENTS.md

MaelNamNam requested a review from a team as a code owner February 13, 2026 10:27

MaelNamNam changed the title ~~✨ feat(rum): add addViewLoadingTime() public API~~ Add addViewLoadingTime() public API Feb 13, 2026

chatgpt-codex-connector bot reviewed Feb 13, 2026

View reviewed changes

MaelNamNam force-pushed the mael.lilensten/manually_report_view_loading_time branch from f4e1030 to 169989b Compare February 13, 2026 10:32

thomas-lebeau reviewed Feb 13, 2026

View reviewed changes

MaelNamNam marked this pull request as draft February 13, 2026 19:10

MaelNamNam mentioned this pull request Feb 16, 2026

[RUM-14619] Add AddViewLoadingTime telemetry to browser schema DataDog/rum-events-format#352

Draft

MaelNamNam force-pushed the mael.lilensten/manually_report_view_loading_time branch from cc33dd8 to c25c762 Compare February 17, 2026 10:40

MaelNamNam changed the title ~~Add addViewLoadingTime() public API~~ [RUM-14619] Add addViewLoadingTime() public API Feb 17, 2026

MaelNamNam force-pushed the mael.lilensten/manually_report_view_loading_time branch from 46d9511 to 7d86ef3 Compare February 18, 2026 21:17

MaelNamNam added 8 commits February 26, 2026 14:35

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[RUM-14619] Add addViewLoadingTime() public API#4180

[RUM-14619] Add addViewLoadingTime() public API#4180
MaelNamNam wants to merge 11 commits intomainfrom
mael.lilensten/manually_report_view_loading_time

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		no_active_view: isResult && 'no_active_view' in result,
		overwritten: isResult && 'overwritten' in result && result.overwritten !== false,

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MaelNamNam commented Feb 13, 2026 •

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