⚗️ Add instrumentConstructor utility by bdibon · Pull Request #4714 · DataDog/browser-sdk

bdibon · 2026-06-03T11:35:00Z

Motivation

In order to instrument WebSocket connections, we need to wrap the WebSocket constructor, so far the instrumentMethod only supports instrumenting regular methods. This PR adds another utility instrumentConstructor supporting the instrumentation of constructor functions.

Changes

Add an instrumentConstructor utility that supports instrumenting constructor functions
Factorize logic between instrumentMethod and new instrumentConstructorutils
Add exhaustive unit tests for instrumentConstructor

Test instructions

yarn test:unit --spec packages/core/src/tools/instrumentMethod.spec.ts

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

bdibon · 2026-06-03T11:35:22Z

This stack of pull requests is managed by Graphite. Learn more about stacking.

cit-pr-commenter-54b7da · 2026-06-03T11:37:21Z

Bundles Sizes Evolution

📦 Bundle Name	Base Size	Local Size	𝚫	𝚫%	Status
Rum	172.08 KiB	172.19 KiB	+106 B	+0.06%	✅
Rum Profiler	7.88 KiB	7.88 KiB	0 B	0.00%	✅
Rum Recorder	21.21 KiB	21.22 KiB	+9 B	+0.04%	✅
Logs	54.60 KiB	54.69 KiB	+94 B	+0.17%	✅
Rum Slim	129.90 KiB	129.99 KiB	+94 B	+0.07%	✅
Worker	22.96 KiB	22.96 KiB	0 B	0.00%	✅

chatgpt-codex-connector

💡 Codex Review

Here are some automated review suggestions for this pull request.

Reviewed commit: c445e3c783

ℹ️ About Codex in GitHub

Your team has set up Codex to review pull requests in this repo. Reviews are triggered when you

Open a pull request for review
Mark a draft as ready
Comment "@codex review".

If Codex has suggestions, it will comment; otherwise it will react with 👍.

Codex can also answer questions or update the PR. Try commenting "@codex address that feedback".

datadog-official · 2026-06-03T11:38:32Z

Tests

🎉 All green!

🧪 All tests passed
❄️ No new flaky tests detected

🎯 Code Coverage (details)
• Patch Coverage: 86.11%
• Overall Coverage: 76.81% (+0.03%)

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

🔗 Commit SHA: 25ddf41 | Docs | Datadog PR Page | Give us feedback!}

chatgpt-codex-connector

💡 Codex Review

Here are some automated review suggestions for this pull request.

Reviewed commit: e2bdea2f62

ℹ️ About Codex in GitHub

Your team has set up Codex to review pull requests in this repo. Reviews are triggered when you

Open a pull request for review
Mark a draft as ready
Comment "@codex review".

If Codex has suggestions, it will comment; otherwise it will react with 👍.

Codex can also answer questions or update the PR. Try commenting "@codex address that feedback".

chatgpt-codex-connector

💡 Codex Review

Here are some automated review suggestions for this pull request.

Reviewed commit: 0b52da5151

ℹ️ About Codex in GitHub

Your team has set up Codex to review pull requests in this repo. Reviews are triggered when you

Open a pull request for review
Mark a draft as ready
Comment "@codex review".

If Codex has suggestions, it will comment; otherwise it will react with 👍.

Codex can also answer questions or update the PR. Try commenting "@codex address that feedback".

chatgpt-codex-connector

💡 Codex Review

Here are some automated review suggestions for this pull request.

Reviewed commit: 0f0b7a0fda

ℹ️ About Codex in GitHub

Your team has set up Codex to review pull requests in this repo. Reviews are triggered when you

Open a pull request for review
Mark a draft as ready
Comment "@codex review".

If Codex has suggestions, it will comment; otherwise it will react with 👍.

Codex can also answer questions or update the PR. Try commenting "@codex address that feedback".

chatgpt-codex-connector

💡 Codex Review

Here are some automated review suggestions for this pull request.

Reviewed commit: 751858d195

ℹ️ About Codex in GitHub

Your team has set up Codex to review pull requests in this repo. Reviews are triggered when you

Open a pull request for review
Mark a draft as ready
Comment "@codex review".

If Codex has suggestions, it will comment; otherwise it will react with 👍.

Codex can also answer questions or update the PR. Try commenting "@codex address that feedback".

chatgpt-codex-connector

💡 Codex Review

Here are some automated review suggestions for this pull request.

Reviewed commit: 201cc19f39

ℹ️ About Codex in GitHub

Your team has set up Codex to review pull requests in this repo. Reviews are triggered when you

Open a pull request for review
Mark a draft as ready
Comment "@codex review".

If Codex has suggestions, it will comment; otherwise it will react with 👍.

Codex can also answer questions or update the PR. Try commenting "@codex address that feedback".

bcaudan · 2026-06-09T09:05:05Z

+export function instrumentConstructor<CONTAINER extends { [key: string]: any }, CONSTRUCTOR extends keyof CONTAINER>(
+  container: CONTAINER,


💬 suggestion: ‏is there a difference between CONTAINER and TARGET? if not, let's use the same term

It's semantics.

With instrumentMethod the target will also be the this value of instrumentation / original, so this is TARGET, I can wrap my head around this one.

With instrumentConstructor, in the normal usage (when it's called with new), the this value refers to the instance being constructed, "target" feels weird in this case, since we're really interested in the (global) object holding the reference to the function we're instrumenting.

Wdyt?

Could it make sense to use CONTAINER for both instrumentMethod and instrumentConstructor?
Since the type parameter describes the object holding the reference and the this value is already surfaced through target in InstrumentedMethodCall for callers who need it.

I would leave it as is, it makes sense to have targetPrototype / TARGET for instrumentMethod and container / CONTAINER for instrumentConstructor.

I'll wait for a third pair of eyes to come by.

BenoitZugmeyer

I'm impressed!

Co-authored-by: Cursor <cursoragent@cursor.com>

…d method after stop

This was referenced Jun 3, 2026

⚗️ Collect WebSocket resource events #4718

Open

✨ Add trackWebSockets configuration option (default: false) #4717

Draft

🔧 Sync rum-events-format with WebSocket resource schema #4716

Draft

bdibon mentioned this pull request Jun 3, 2026

⚗️ Add webSocketObservable for WebSocket lifecycle events #4715

Draft

5 tasks

bdibon marked this pull request as ready for review June 3, 2026 11:36

bdibon requested a review from a team as a code owner June 3, 2026 11:36

chatgpt-codex-connector Bot reviewed Jun 3, 2026

View reviewed changes

Comment thread packages/core/src/tools/instrumentMethod.ts Outdated

Comment thread packages/browser-core/src/tools/instrumentMethod.ts Outdated

bdibon force-pushed the boris.dibon/ws-1-instrument-method-constructor branch from c445e3c to e2bdea2 Compare June 4, 2026 09:16

chatgpt-codex-connector Bot reviewed Jun 4, 2026

View reviewed changes

Comment thread packages/browser-core/src/tools/instrumentMethod.ts Outdated

bcaudan reviewed Jun 4, 2026

View reviewed changes

chatgpt-codex-connector Bot reviewed Jun 4, 2026

View reviewed changes

Comment thread packages/browser-core/src/tools/instrumentMethod.ts Outdated

Comment thread packages/browser-core/src/tools/instrumentMethod.ts Outdated

chatgpt-codex-connector Bot reviewed Jun 4, 2026

View reviewed changes

Comment thread packages/browser-core/src/tools/instrumentMethod.ts Outdated

Comment thread packages/browser-core/src/tools/instrumentMethod.ts Outdated

Comment thread packages/browser-core/src/tools/instrumentMethod.ts Outdated

bcaudan reviewed Jun 5, 2026

View reviewed changes

bdibon force-pushed the boris.dibon/ws-1-instrument-method-constructor branch from 0f0b7a0 to 751858d Compare June 8, 2026 11:17

chatgpt-codex-connector Bot reviewed Jun 8, 2026

View reviewed changes

Comment thread packages/browser-core/src/tools/instrumentMethod.ts Outdated

chatgpt-codex-connector Bot reviewed Jun 8, 2026

View reviewed changes

Comment thread packages/browser-core/src/tools/instrumentMethod.ts

bdibon force-pushed the boris.dibon/ws-1-instrument-method-constructor branch from 201cc19 to 8d89c48 Compare June 8, 2026 15:12

mormubis reviewed Jun 8, 2026

View reviewed changes

Comment thread packages/browser-core/src/tools/instrumentMethod.ts

bdibon changed the title ~~✨ Add constructor support to instrumentMethod~~ ✨ Add instrumentConstructor utility Jun 8, 2026

bdibon changed the title ~~✨ Add instrumentConstructor utility~~ ⚗️ Add instrumentConstructor utility Jun 8, 2026

bcaudan approved these changes Jun 9, 2026

View reviewed changes

BenoitZugmeyer reviewed Jun 9, 2026

View reviewed changes

Comment thread packages/browser-core/src/tools/instrumentMethod.spec.ts Outdated

Comment thread packages/browser-core/src/tools/instrumentMethod.ts Outdated

Comment thread packages/browser-core/src/tools/instrumentMethod.ts Outdated

bdibon and others added 5 commits June 10, 2026 10:13

✨ Add constructor support to instrumentMethod

be4dc35

Co-authored-by: Cursor <cursoragent@cursor.com>

👌 Handle subclassing instrumentation

b8caa77

✅ Test after stop() behavior

26fb7c0

👌 Preserve static members

cfeedfa

👌 Preserve original new.target when instrumentation is called directly

a5a574a

bdibon added 17 commits June 10, 2026 10:13

👌 Replace WebSocket occurences with MyClass

714c672

👌 Merge duplicated code branches

7b704aa

👌 Separate constructor from method instrumentation logic

554b0fc

👌 Preserve new.target when constructing a subclass of the instrumente…

8135d02

…d method after stop

👌 Outline limitation of static members preservation

6cda371

👌 Preserve prototype.constructor

12f9fcb

👌 Do not instrument calls when class constructor is called without new

a0bb54f

👌 Preserve original.prototype descriptor on instrumentation

006d9fb

🎨 Improve code structure

6b008b8

👌 Add "instrumented constructor" type to handling stack

86cb048

👌 Test parity with instrumentMethod

d2df0be

♻️ Simplify code to our use case

988c801

👌 Improve naming convention for instrumentConstructor

d36d1fa

✅ Add test for constructor's prototype descriptor writable value

a061379

👌 Test after stop leaves third party prototype.constructor

6b06fc5

👌 Improve tests fixture

42f55be

👌 Improve readability

a191d86

bdibon force-pushed the boris.dibon/ws-1-instrument-method-constructor branch from 8d89c48 to a191d86 Compare June 10, 2026 09:09

bdibon requested a review from BenoitZugmeyer June 10, 2026 09:10

BenoitZugmeyer approved these changes Jun 10, 2026

View reviewed changes

Comment thread packages/browser-core/src/tools/instrumentMethod.ts Outdated

👌 Reuse replaceWithInstrumentation in preserveConstructorShape

25ddf41

bdibon merged commit 25ec8c5 into main Jun 10, 2026
31 checks passed

bdibon deleted the boris.dibon/ws-1-instrument-method-constructor branch June 10, 2026 12:12

github-actions Bot locked and limited conversation to collaborators Jun 10, 2026

		export function instrumentConstructor<CONTAINER extends { [key: string]: any }, CONSTRUCTOR extends keyof CONTAINER>(
		container: CONTAINER,

Conversation

bdibon commented Jun 3, 2026 • edited Loading Uh oh! There was an error while loading. Please reload this page.

Uh oh!

Motivation

Changes

Test instructions

Checklist

Uh oh!

bdibon commented Jun 3, 2026 • edited Loading Uh oh! There was an error while loading. Please reload this page.

Uh oh!

Uh oh!

cit-pr-commenter-54b7da Bot commented Jun 3, 2026 • edited Loading Uh oh! There was an error while loading. Please reload this page.

Uh oh!

Bundles Sizes Evolution

Uh oh!

chatgpt-codex-connector Bot left a comment

Choose a reason for hiding this comment

💡 Codex Review

Uh oh!

Uh oh!

Uh oh!

datadog-official Bot commented Jun 3, 2026 • edited Loading Uh oh! There was an error while loading. Please reload this page.

Uh oh!

Uh oh!

chatgpt-codex-connector Bot left a comment

Choose a reason for hiding this comment

💡 Codex Review

Uh oh!

Uh oh!

Uh oh!

Uh oh!

Uh oh!

Uh oh!

chatgpt-codex-connector Bot left a comment

Choose a reason for hiding this comment

💡 Codex Review

Uh oh!

Uh oh!

Uh oh!

chatgpt-codex-connector Bot left a comment

Choose a reason for hiding this comment

💡 Codex Review

Uh oh!

Uh oh!

Uh oh!

Uh oh!

Uh oh!

Uh oh!

Uh oh!

Uh oh!

Uh oh!

chatgpt-codex-connector Bot left a comment

Choose a reason for hiding this comment

💡 Codex Review

Uh oh!

Uh oh!

chatgpt-codex-connector Bot left a comment

Choose a reason for hiding this comment

💡 Codex Review

Uh oh!

Uh oh!

Uh oh!

bcaudan Jun 9, 2026

Choose a reason for hiding this comment

Uh oh!

bdibon Jun 9, 2026

Choose a reason for hiding this comment

Uh oh!

bcaudan Jun 9, 2026

Choose a reason for hiding this comment

Uh oh!

bdibon Jun 9, 2026

Choose a reason for hiding this comment

Uh oh!

BenoitZugmeyer left a comment

Choose a reason for hiding this comment

Uh oh!

Uh oh!

Uh oh!

Uh oh!

bdibon commented Jun 3, 2026 •

edited

Loading

bdibon commented Jun 3, 2026 •

edited

Loading

cit-pr-commenter-54b7da Bot commented Jun 3, 2026 •

edited

Loading

datadog-official Bot commented Jun 3, 2026 •

edited

Loading