Collapse multiple text mutations when frozen / throttled by eoghanmurray · Pull Request #1933 · rrweb-io/rrweb

eoghanmurray · 2026-09-08T12:03:54Z

This PR does two things:

Ensure we don't emit multiple text or attribute mutations against the same node while throttled or when mutations are frozen
Pull in the 'configurable throttling on mutation emission' from Implement configurable throttling on mutation emission #1694 but re-implement on a per-element basis, so a change to a well behaved element isn't delayed by another noisier one

Replay should be unaffected, as the replayer would have applied the last mutation in the series, which should end up in the same state at that timestamp. The test data shows some de-duplication of text/attributes after this change, which is proof positive.

Tech note:

Also recognize that the additional WeakMap added in perf(rrweb): attribute mutation optimization #1343 in relation to attributes/attributeMap can be improved by replacing both variables with a single Map. The array was holding strong references to the Node anyway in the attributeCursor; these were freed at the end after // reset and this is still the case after this change

changeset-bot · 2026-09-08T12:04:00Z

🦋 Changeset detected

Latest commit: c7d2802

The changes in this PR will be included in the next version bump.

This PR includes changesets to release 22 packages

Name	Type
rrweb	Patch
@rrweb/record	Patch
@rrweb/types	Patch
@rrweb/all	Patch
@rrweb/browser-client	Patch
@rrweb/packer	Patch
@rrweb/replay	Patch
rrdom-nodejs	Patch
rrdom	Patch
rrvideo	Patch
rrweb-player	Patch
rrweb-snapshot	Patch
@rrweb/utils	Patch
@rrweb/web-extension	Patch
@rrweb/rrweb-plugin-canvas-webrtc-record	Patch
@rrweb/rrweb-plugin-canvas-webrtc-replay	Patch
@rrweb/rrweb-plugin-console-record	Patch
@rrweb/rrweb-plugin-console-replay	Patch
@rrweb/rrweb-plugin-network-record	Patch
@rrweb/rrweb-plugin-network-replay	Patch
@rrweb/rrweb-plugin-sequential-id-record	Patch
@rrweb/rrweb-plugin-sequential-id-replay	Patch

Not sure what this means? Click here to learn what changesets are.

Click here if you're a maintainer who wants to add another changeset to this PR

github-actions · 2026-09-08T12:09:46Z

Bundle Size Changes

Size change: +1.42 kB (+0.01%) | Total size: 10430.46 kB

all - 1975.72 kB -> 1976.08 kB (+364 B (+0.02%))

File	Base	PR	Diff
`all.cjs`	567.91 kB	568.03 kB	+121 B (+0.02%)
`all.js`	567.58 kB	567.70 kB	+121 B (+0.02%)
`all.umd.cjs`	571.12 kB	571.24 kB	+121 B (+0.02%)
`all.umd.min.cjs`	269.12 kB	269.12 kB	+1 B (+0.00%)

browser-client - 670.07 kB -> 670.42 kB (+364 B (+0.05%))

File	Base	PR	Diff
`browser-client.cjs`	192.15 kB	192.26 kB	+121 B (+0.06%)
`browser-client.js`	191.92 kB	192.04 kB	+121 B (+0.06%)
`browser-client.umd.cjs`	194.97 kB	195.09 kB	+121 B (+0.06%)
`browser-client.umd.min.cjs`	91.03 kB	91.03 kB	+1 B (+0.00%)

record - 552.68 kB -> 553.04 kB (+364 B (+0.06%))

File	Base	PR	Diff
`record.cjs`	158.46 kB	158.58 kB	+121 B (+0.07%)
`record.js`	158.38 kB	158.49 kB	+121 B (+0.07%)
`record.umd.cjs`	159.79 kB	159.91 kB	+121 B (+0.07%)
`record.umd.min.cjs`	76.05 kB	76.06 kB	+1 B (+0.00%)

rrweb - 1913.90 kB -> 1914.26 kB (+364 B (+0.02%))

File	Base	PR	Diff
`rrweb.cjs`	551.07 kB	551.19 kB	+121 B (+0.02%)
`rrweb.js`	550.77 kB	550.89 kB	+121 B (+0.02%)
`rrweb.umd.cjs`	552.29 kB	552.41 kB	+121 B (+0.02%)
`rrweb.umd.min.cjs`	259.77 kB	259.78 kB	+1 B (+0.00%)

pkg-pr-new · 2026-09-09T11:54:35Z

@rrweb/all

npm i https://pkg.pr.new/rrweb-io/rrweb/@rrweb/all@c7d2802

@rrweb/browser-client

npm i https://pkg.pr.new/rrweb-io/rrweb/@rrweb/browser-client@c7d2802

@rrweb/packer

npm i https://pkg.pr.new/rrweb-io/rrweb/@rrweb/packer@c7d2802

@rrweb/record

npm i https://pkg.pr.new/rrweb-io/rrweb/@rrweb/record@c7d2802

@rrweb/replay

npm i https://pkg.pr.new/rrweb-io/rrweb/@rrweb/replay@c7d2802

rrdom

npm i https://pkg.pr.new/rrweb-io/rrweb/rrdom@c7d2802

rrdom-nodejs

npm i https://pkg.pr.new/rrweb-io/rrweb/rrdom-nodejs@c7d2802

rrvideo

npm i https://pkg.pr.new/rrweb-io/rrweb/rrvideo@c7d2802

rrweb

npm i https://pkg.pr.new/rrweb-io/rrweb@c7d2802

rrweb-player

npm i https://pkg.pr.new/rrweb-io/rrweb/rrweb-player@c7d2802

rrweb-snapshot

npm i https://pkg.pr.new/rrweb-io/rrweb/rrweb-snapshot@c7d2802

@rrweb/types

npm i https://pkg.pr.new/rrweb-io/rrweb/@rrweb/types@c7d2802

@rrweb/utils

npm i https://pkg.pr.new/rrweb-io/rrweb/@rrweb/utils@c7d2802

@rrweb/rrweb-plugin-canvas-webrtc-record

npm i https://pkg.pr.new/rrweb-io/rrweb/@rrweb/rrweb-plugin-canvas-webrtc-record@c7d2802

@rrweb/rrweb-plugin-canvas-webrtc-replay

npm i https://pkg.pr.new/rrweb-io/rrweb/@rrweb/rrweb-plugin-canvas-webrtc-replay@c7d2802

@rrweb/rrweb-plugin-console-record

npm i https://pkg.pr.new/rrweb-io/rrweb/@rrweb/rrweb-plugin-console-record@c7d2802

@rrweb/rrweb-plugin-console-replay

npm i https://pkg.pr.new/rrweb-io/rrweb/@rrweb/rrweb-plugin-console-replay@c7d2802

@rrweb/rrweb-plugin-network-record

npm i https://pkg.pr.new/rrweb-io/rrweb/@rrweb/rrweb-plugin-network-record@c7d2802

@rrweb/rrweb-plugin-network-replay

npm i https://pkg.pr.new/rrweb-io/rrweb/@rrweb/rrweb-plugin-network-replay@c7d2802

@rrweb/rrweb-plugin-sequential-id-record

npm i https://pkg.pr.new/rrweb-io/rrweb/@rrweb/rrweb-plugin-sequential-id-record@c7d2802

@rrweb/rrweb-plugin-sequential-id-replay

npm i https://pkg.pr.new/rrweb-io/rrweb/@rrweb/rrweb-plugin-sequential-id-replay@c7d2802

commit: c7d2802

…mutations are frozen

…on that this PR fixes; the text is only set to 'yellow' in the test once

…e e.g. style attribute diffs over and over while frozen or during throttling - this mirrors the other pattern from this PR for text mutations - more importantly, the serialization of new 'add' nodes has always happened upon emission, so the deferred computation is by design (no point in serializing something that may have been added then quickly removed)

…`sampling.mutation` ms setting - can prevent overly frequent (javascript based) animation per second on the same attribute; the mutation buffer will emit a single change at the end if throttled changes are against the same element

…default in rrweb package; useful for experimenting with live-stream in worktrees where there's been no previous build

… attributes/textContent on a per-element basis rather than globally (so a noisy element can't delay a well behaved one)

…const)

eoghanmurray force-pushed the collapse-frozen-mutations branch from ce9ff62 to 179b3f9 Compare September 8, 2026 12:04

eoghanmurray mentioned this pull request Sep 8, 2026

perf(rrweb): attribute mutation optimization #1343

Merged

pauldambra mentioned this pull request Sep 8, 2026

Track upstream rrweb changes to pull in PostHog/posthog-js#3765

Open

eoghanmurray force-pushed the collapse-frozen-mutations branch from a8e5ab7 to 365f778 Compare September 9, 2026 11:50

eoghanmurray added 3 commits September 21, 2026 13:13

Ensure we don't emit multiple text mutations while throttled or when …

587a32a

…mutations are frozen

Add changeset

693ba50

Fixup style mutation test: a good example of a duplicated text emissi…

38d7cdf

…on that this PR fixes; the text is only set to 'yellow' in the test once

eoghanmurray mentioned this pull request Sep 21, 2026

Implement configurable throttling on mutation emission #1694

Closed

eoghanmurray added 7 commits September 21, 2026 22:53

Create friendly-rockets-live.md

b24b07c

when src/record is changed, add @rrweb/record

359bd2f

live-stream relies on the canvas-webrtc plugin but it's not built by …

0d306df

…default in rrweb package; useful for experimenting with live-stream in worktrees where there's been no previous build

Add test for mutation throttling

6d8da1d

Improve the #1694 throttling to focus on throttling emission of noisy…

49c6e6c

… attributes/textContent on a per-element basis rather than globally (so a noisy element can't delay a well behaved one)

eoghanmurray force-pushed the collapse-frozen-mutations branch from 365f778 to 49c6e6c Compare September 21, 2026 22:00

Apply formatting changes

2c5d4ed

eoghanmurray mentioned this pull request Sep 21, 2026

feat(record): add attributeFilter option for native MutationObserver filtering #1873

Open

eoghanmurray added 2 commits September 22, 2026 10:51

Fix eslint for maybeSentinel which could be const (name can't be …

69bd2a2

…const)

Update docs to match behaviour

c7d2802

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Collapse multiple text mutations when frozen / throttled - #1933

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