buffer: add isLatin1 by jasnell · Pull Request #66298 · nodejs/node

jasnell · 2026-09-25T19:02:26Z

Implements a fast check to determine if a string is ~~Latin1~~ ~~a byte string~~ Latin1.

Can be many times faster than the equivalent regex check.

input	isByteString	regex	loop
short, one-byte	232M	122M	55M
short, two-byte	207M	130M	56M
short, invalid	106M	48M	53M
long, one-byte	221M	93M	230k
long, two-byte	6.7M	913k	186k
long, invalid	75M	914k	234k

(the larger perf gap there is with concatenated strings)

nodejs-github-bot · 2026-09-25T19:02:31Z

Review requested:

@nodejs/performance

aduh95 · 2026-09-25T19:08:14Z

I don't think isLatin1 is a good name, \u0100 can definitely be a 2-byte latin1 string

jasnell · 2026-09-25T19:09:12Z

Yeah, I'm going to rename to isByteString ... it matches the webidl usage better.

nodejs-github-bot · 2026-09-25T19:43:02Z

CI: https://ci.nodejs.org/job/node-test-pull-request/77917/ 💚

codecov · 2026-09-25T21:47:53Z

Codecov Report

❌ Patch coverage is 88.46154% with 3 lines in your changes missing coverage. Please review.
✅ Project coverage is 90.35%. Comparing base (3641c36) to head (799740c).
⚠️ Report is 6 commits behind head on main.

Files with missing lines	Patch %	Lines
src/node_buffer.cc	76.92%	0 Missing and 3 partials ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main   #66298      +/-   ##
==========================================
- Coverage   90.36%   90.35%   -0.01%     
==========================================
  Files         792      792              
  Lines      275386   275412      +26     
  Branches    52770    52786      +16     
==========================================
+ Hits       248859   248860       +1     
- Misses      16936    16973      +37     
+ Partials     9591     9579      -12

Files with missing lines	Coverage Δ
lib/buffer.js	`99.74% <100.00%> (+<0.01%)`	⬆️
src/node_buffer.cc	`70.48% <76.92%> (+0.06%)`	⬆️

... and 25 files with indirect coverage changes

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addaleax

isLatin1String would be much better naming because it describes what the method actually tests for. The WebIDL ByteString type describes a legacy type that stems from the lack of commitment to a specific encoding in early HTTP versions other than vague ASCII backwards compatibility, and it's not actually used widely outside of HTTP-specific APIs for that (very good) reason.

I don't think isLatin1 is a good name, \u0100 can definitely be a 2-byte latin1 string

This is not a statement that makes sense, \u0100 cannot be represented in Latin-1, and there are, by definition, no 2-byte Latin-1 strings to begin with -- maybe you're referring to the idea that the byte sequence 01 00 can be Latin-1, but this method takes a string as an argument, i.e. a character sequence, not a byte sequence

Implements a fast check to determine if a string is a valid byte string (only chars <= 0xff). Signed-off-by: James M Snell <jasnell@gmail.com> PR-URL: #66298 Reviewed-By: René <contact.9a5d6388@renegade334.me.uk> Reviewed-By: Filip Skokan <panva.ip@gmail.com> Reviewed-By: Anna Henningsen <anna@addaleax.net> Reviewed-By: Robert Nagy <ronagy@icloud.com>

nodejs-github-bot · 2026-09-28T04:23:00Z

Landed in b59840b

jasnell · 2026-09-28T04:23:00Z

Landed in 8f43e88

MikeMcC399 · 2026-09-28T05:38:24Z

Looks like it was landed twice: first through commit-queue and once through manual actions, so the later commit b59840b is an empty commit.

Implements a fast check to determine if a string is a valid byte string (only chars <= 0xff). Signed-off-by: James M Snell <jasnell@gmail.com> PR-URL: nodejs#66298 Reviewed-By: René <contact.9a5d6388@renegade334.me.uk> Reviewed-By: Filip Skokan <panva.ip@gmail.com> Reviewed-By: Anna Henningsen <anna@addaleax.net> Reviewed-By: Robert Nagy <ronagy@icloud.com>

jasnell · 2026-09-28T08:57:05Z

Ugh, I think that's happened before also. I removed the commit-queue label and landed it manually because I had convinced myself somehow that the commit was going to need to be tweaked before merging but then realized it was fine.

Implements a fast check to determine if a string is a valid byte string (only chars <= 0xff). Signed-off-by: James M Snell <jasnell@gmail.com> PR-URL: #66298 Reviewed-By: René <contact.9a5d6388@renegade334.me.uk> Reviewed-By: Filip Skokan <panva.ip@gmail.com> Reviewed-By: Anna Henningsen <anna@addaleax.net> Reviewed-By: Robert Nagy <ronagy@icloud.com>

Implements a fast check to determine if a string is a valid byte string (only chars <= 0xff). Signed-off-by: James M Snell <jasnell@gmail.com> PR-URL: nodejs#66298 Reviewed-By: René <contact.9a5d6388@renegade334.me.uk> Reviewed-By: Filip Skokan <panva.ip@gmail.com> Reviewed-By: Anna Henningsen <anna@addaleax.net> Reviewed-By: Robert Nagy <ronagy@icloud.com>

Notable changes: benchmark: * (SEMVER-MINOR) add http header validator benchmark (James M Snell) #66334 buffer: * (SEMVER-MINOR) add isLatin1 (James M Snell) #66298 * (SEMVER-MINOR) add isLatin1 (James M Snell) #66298 * (SEMVER-MINOR) add Buffer.stringLength() (Matteo Collina) #66064 build, doc: * move to redesign (Aviv Keller) #62045 http: * (SEMVER-MINOR) add isValidHeaderName() and isValidHeaderValue() (James M Snell) #66334 http2: * (SEMVER-MINOR) add new connectionWindowSize option (Tim Perry) #65619 lib: * (SEMVER-MINOR) fix stream loading bug in node:bench (James M Snell) #66114 perf_hooks: * (SEMVER-MINOR) fix truncation of monitorEventLoopDelay() resolution (James M Snell) #66115 * (SEMVER-MINOR) allow RecordableHistogram to record 0 (James M Snell) #66114 * (SEMVER-MINOR) add histogram.diff() (James M Snell) #66099 * (SEMVER-MINOR) report histogram memory to V8 (James M Snell) #66099 * (SEMVER-MINOR) add histogram.snapshot() (James M Snell) #66099 * (SEMVER-MINOR) add histogram export format version 2 (James M Snell) #66098 * (SEMVER-MINOR) harden histogram CBOR import validation (James M Snell) #66098 process: * (SEMVER-MINOR) graduate process.ref/unref from experimental (James M Snell) #66213 sqlite: * (SEMVER-MINOR) rename DatabaseSync and StatementSync (Guilherme Araújo) #65988 src: * (SEMVER-MINOR) add --process-timeout=N (James M Snell) #66138 * (SEMVER-MINOR) expose size and count in heap profile output (Ilyas Shabi) #65737 * (SEMVER-MINOR) let embedders exempt linked bindings from the addon permission (Shelley Vohr) #66067 test: * deflake sliding window histogram test (James M Snell) #66132 PR-URL: #66546

Notable changes: buffer: * (SEMVER-MINOR) add isLatin1 (James M Snell) #66298 * (SEMVER-MINOR) add Buffer.stringLength() (Matteo Collina) #66064 build, doc: * move to redesign (Aviv Keller) #62045 http: * (SEMVER-MINOR) add isValidHeaderName() and isValidHeaderValue() (James M Snell) #66334 http2: * (SEMVER-MINOR) add new connectionWindowSize option (Tim Perry) #65619 perf_hooks: * (SEMVER-MINOR) fix truncation of monitorEventLoopDelay() resolution (James M Snell) #66115 * (SEMVER-MINOR) allow RecordableHistogram to record 0 (James M Snell) #66114 * (SEMVER-MINOR) add histogram.diff() (James M Snell) #66099 * (SEMVER-MINOR) report histogram memory to V8 (James M Snell) #66099 * (SEMVER-MINOR) add histogram.snapshot() (James M Snell) #66099 * (SEMVER-MINOR) add histogram export format version 2 (James M Snell) #66098 * (SEMVER-MINOR) harden histogram CBOR import validation (James M Snell) #66098 process: * (SEMVER-MINOR) graduate process.ref/unref from experimental (James M Snell) #66213 sqlite: * (SEMVER-MINOR) rename DatabaseSync and StatementSync (Guilherme Araújo) #65988 src: * (SEMVER-MINOR) add --process-timeout=N (James M Snell) #66138 * (SEMVER-MINOR) expose size and count in heap profile output (Ilyas Shabi) #65737 * (SEMVER-MINOR) let embedders exempt linked bindings from the addon permission (Shelley Vohr) #66067 PR-URL: #66546

Notable changes: buffer: * (SEMVER-MINOR) add isLatin1 (James M Snell) #66298 * (SEMVER-MINOR) add Buffer.stringLength() (Matteo Collina) #66064 build, doc: * move to redesign (Aviv Keller) #62045 doc: * promote Alpine Linux to tier 2 support (Stewart X Addison) #63737 http: * (SEMVER-MINOR) add isValidHeaderName() and isValidHeaderValue() (James M Snell) #66334 http2: * (SEMVER-MINOR) add new connectionWindowSize option (Tim Perry) #65619 perf_hooks: * (SEMVER-MINOR) fix truncation of monitorEventLoopDelay() resolution (James M Snell) #66115 * (SEMVER-MINOR) allow RecordableHistogram to record 0 (James M Snell) #66114 * (SEMVER-MINOR) add histogram.diff() (James M Snell) #66099 * (SEMVER-MINOR) add histogram.snapshot() (James M Snell) #66099 * (SEMVER-MINOR) harden histogram CBOR import validation (James M Snell) #66098 process: * (SEMVER-MINOR) graduate process.ref/unref from experimental (James M Snell) #66213 sqlite: * (SEMVER-MINOR) rename DatabaseSync and StatementSync (Guilherme Araújo) #65988 src: * (SEMVER-MINOR) add --process-timeout=N (James M Snell) #66138 * (SEMVER-MINOR) expose size and count in heap profile output (Ilyas Shabi) #65737 * (SEMVER-MINOR) let embedders exempt linked bindings from the addon permission (Shelley Vohr) #66067 PR-URL: #66546

jasnell requested review from mcollina, ronag and trivikr September 25, 2026 19:02

nodejs-github-bot added buffer Issues and PRs related to the buffer subsystem. c++ Issues and PRs that require attention from people who are familiar with C++. needs-ci PRs that need a full CI run. labels Sep 25, 2026

jasnell mentioned this pull request Sep 25, 2026

perf(webidl): check ByteString code units with a native scan nodejs/undici#5903

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4 of 7 tasks

jasnell force-pushed the jasnell/islatin1 branch from 5826c3c to 98b8ffc Compare September 25, 2026 19:13

jasnell changed the title ~~buffer: add isLatin1~~ buffer: add isByteString Sep 25, 2026

jasnell added the semver-minor PRs that contain new features and should be released in the next minor version. label Sep 25, 2026

jasnell requested a review from aduh95 September 25, 2026 19:28

Renegade334 reviewed Sep 25, 2026

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Comment thread src/node_buffer.cc Outdated

jasnell force-pushed the jasnell/islatin1 branch from 98b8ffc to 07f71ca Compare September 25, 2026 19:37

jasnell requested a review from Renegade334 September 25, 2026 19:37

Renegade334 approved these changes Sep 25, 2026

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jasnell force-pushed the jasnell/islatin1 branch from 07f71ca to 090b087 Compare September 25, 2026 19:41

panva approved these changes Sep 25, 2026

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Renegade334 approved these changes Sep 25, 2026

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jasnell added the commit-queue PRs queued for automated landing through the Commit Queue. label Sep 26, 2026

panva mentioned this pull request Sep 26, 2026

buffer: add missing binding typings #66328

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addaleax requested changes Sep 26, 2026

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addaleax removed the author ready PRs with CI started, the required approvals, and no outstanding review comments. label Sep 26, 2026

nodejs-github-bot merged commit b59840b into nodejs:main Sep 28, 2026
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github-actions Bot mentioned this pull request Oct 5, 2026

2026-10-07, Version 26.11.0 (Current) #66546

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buffer: add isLatin1 - #66298

buffer: add isLatin1#66298
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