lib: use Object.freeze to avoid defensive cloning in SourceMap by watilde · Pull Request #62830 · nodejs/node

watilde · 2026-04-19T10:37:36Z

No description provided.

codecov · 2026-04-19T11:58:49Z

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 89.65%. Comparing base (d44a71a) to head (673e0a2).
⚠️ Report is 264 commits behind head on main.

Additional details and impacted files

@@ Coverage Diff @@## main #62830 +/- ##
==========================================
+ Coverage 89.61% 89.65% +0.03% 
==========================================
Files 706 706 Lines 219203 219389 +186 Branches 41995 42061 +66 ==========================================
+ Hits 196445 196692 +247 + Misses 14663 14589 -74 - Partials 8095 8108 +13

Files with missing lines	Coverage Δ
lib/internal/source_map/source_map.js	`99.48% <100.00%> (+0.25%)`	⬆️

... and 49 files with indirect coverage changes

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legendecas

Would you mind adding a note on https://github.com/nodejs/node/blob/main/doc/api/module.md#sourcemappayload that the returned payload is frozen? Thanks!

legendecas

Would you mind fixing the linter complaints? Thanks

watilde · 2026-04-23T11:09:03Z

Fix, rebase and make the commit Verified.

Co-authored-by: Chengzhong Wu <legendecas@gmail.com>

nodejs-github-bot · 2026-04-25T16:24:18Z

CI: https://ci.nodejs.org/job/node-test-pull-request/72922/

nodejs-github-bot · 2026-05-19T14:32:59Z

Commit Queue failed

- Loading data for nodejs/node/pull/62830
✔ Done loading data for nodejs/node/pull/62830
----------------------------------- PR info ------------------------------------
Title lib: use Object.freeze to avoid defensive cloning in SourceMap (#62830)
Author Daijiro Wachi <daijiro.wachi@gmail.com> (@watilde)
Branch watilde:fixes-memory-sourcemap -> nodejs:main
Labels semver-major, author ready, source maps, commit-queue-squash
Commits 4
- lib: use Object.freeze to avoid defensive cloning in SourceMap
- doc: clarify sourceMap.payload behavior and immutability
- doc: add change metadata for validator message
- doc: fix unclosed YAML comment in sourceMap.payload
Committers 2
- Daijiro Wachi <daijiro.wachi@gmail.com>
- GitHub <noreply@github.com>
PR-URL: https://github.com/nodejs/node/pull/62830
Reviewed-By: Chengzhong Wu <legendecas@gmail.com>
------------------------------ Generated metadata ------------------------------
PR-URL: https://github.com/nodejs/node/pull/62830
Reviewed-By: Chengzhong Wu <legendecas@gmail.com>
--------------------------------------------------------------------------------
ℹ This PR was created on Sun, 19 Apr 2026 10:37:36 GMT
✔ Approvals: 1
✔ - Chengzhong Wu (@legendecas) (TSC): https://github.com/nodejs/node/pull/62830#pullrequestreview-4175823264
✘ semver-major requires at least 2 TSC approvals
✔ Last GitHub CI successful
ℹ Last Full PR CI on 2026-04-25T16:24:18Z: https://ci.nodejs.org/job/node-test-pull-request/72922/
- Querying data for job/node-test-pull-request/72922/
✔ Build data downloaded
✔ Last Jenkins CI successful
--------------------------------------------------------------------------------
✔ Aborted `git node land` session in /home/runner/work/node/node/.ncu

https://github.com/nodejs/node/actions/runs/26103949075

legendecas · 2026-05-19T15:08:47Z

Given that this is a breaking change, this needs another @nodejs/tsc review, thanks!

nodejs-github-bot · 2026-05-19T17:49:08Z

Commit Queue failed

- Loading data for nodejs/node/pull/62830 ✔ Done loading data for nodejs/node/pull/62830 ----------------------------------- PR info ------------------------------------ Title lib: use Object.freeze to avoid defensive cloning in SourceMap (#62830) Author Daijiro Wachi <daijiro.wachi@gmail.com> (@watilde) Branch watilde:fixes-memory-sourcemap -> nodejs:main Labels semver-major, author ready, source maps, commit-queue-squash Commits 4 - lib: use Object.freeze to avoid defensive cloning in SourceMap - doc: clarify sourceMap.payload behavior and immutability - doc: add change metadata for validator message - doc: fix unclosed YAML comment in sourceMap.payload Committers 2 - Daijiro Wachi <daijiro.wachi@gmail.com> - GitHub <noreply@github.com> PR-URL: https://github.com/nodejs/node/pull/62830 Reviewed-By: Chengzhong Wu <legendecas@gmail.com> Reviewed-By: Yagiz Nizipli <yagiz@nizipli.com> ------------------------------ Generated metadata ------------------------------ PR-URL: https://github.com/nodejs/node/pull/62830 Reviewed-By: Chengzhong Wu <legendecas@gmail.com> Reviewed-By: Yagiz Nizipli <yagiz@nizipli.com> -------------------------------------------------------------------------------- ℹ This PR was created on Sun, 19 Apr 2026 10:37:36 GMT ✔ Approvals: 2 ✔ - Chengzhong Wu (@legendecas) (TSC): https://github.com/nodejs/node/pull/62830#pullrequestreview-4175823264 ✔ - Yagiz Nizipli (@anonrig) (TSC): https://github.com/nodejs/node/pull/62830#pullrequestreview-4320305018 ✔ Last GitHub CI successful ℹ Last Full PR CI on 2026-05-19T14:32:59Z: https://ci.nodejs.org/job/node-test-pull-request/72922/ - Querying data for job/node-test-pull-request/72922/ ✔ Build data downloaded ✔ Last Jenkins CI successful -------------------------------------------------------------------------------- ✔ No git cherry-pick in progress ✔ No git am in progress ✔ No git rebase in progress -------------------------------------------------------------------------------- - Bringing origin/main up to date... From https://github.com/nodejs/node * branch main -> FETCH_HEAD ✔ origin/main is now up-to-date - Downloading patch for 62830 From https://github.com/nodejs/node * branch refs/pull/62830/merge -> FETCH_HEAD ✔ Fetched commits as 783b38248310..673e0a2285e9 -------------------------------------------------------------------------------- [main 69cf5e6625] lib: use Object.freeze to avoid defensive cloning in SourceMap Author: Daijiro Wachi <daijiro.wachi@gmail.com> Date: Sun Apr 19 19:40:37 2026 +0900 2 files changed, 19 insertions(+), 8 deletions(-) Auto-merging doc/api/module.md [main 9ca29e4b19] doc: clarify sourceMap.payload behavior and immutability Author: Daijiro Wachi <daijiro.wachi@gmail.com> Date: Thu Apr 23 19:36:22 2026 +0900 1 file changed, 4 insertions(+) Auto-merging doc/api/module.md [main 7b0a139518] doc: add change metadata for validator message Author: Daijiro Wachi <daijiro.wachi@gmail.com> Date: Fri Apr 24 02:52:24 2026 +0900 1 file changed, 5 insertions(+) Auto-merging doc/api/module.md [main 4251de19a1] doc: fix unclosed YAML comment in sourceMap.payload Author: Daijiro Wachi <daijiro.wachi@gmail.com> Date: Sat Apr 25 18:32:39 2026 +0900 1 file changed, 2 insertions(+) ✔ Patches applied There are 4 commits in the PR. Attempting to fixup everything into first commit. [main 1bd0ca9117] lib: use Object.freeze to avoid defensive cloning in SourceMap Author: Daijiro Wachi <daijiro.wachi@gmail.com> Date: Sun Apr 19 19:40:37 2026 +0900 3 files changed, 30 insertions(+), 8 deletions(-) --------------------------------- New Message ---------------------------------- lib: use Object.freeze to avoid defensive cloning in SourceMap

PR-URL: #62830
Reviewed-By: Chengzhong Wu <legendecas@gmail.com>
Reviewed-By: Yagiz Nizipli <yagiz@nizipli.com>

[main c2e25ee445] lib: use Object.freeze to avoid defensive cloning in SourceMap
Author: Daijiro Wachi <daijiro.wachi@gmail.com>
Date: Sun Apr 19 19:40:37 2026 +0900
3 files changed, 30 insertions(+), 8 deletions(-)
✖ c2e25ee4458f66a963f8dfaa3f456d6744cdf674
✔ 0:0 no Assisted-by metadata assisted-by-is-trailer
✔ 0:0 no Co-authored-by metadata co-authored-by-is-trailer
✔ 0:0 skipping fixes-url fixes-url
✔ 0:0 blank line after title line-after-title
✔ 0:0 line-lengths are valid line-length
✔ 0:0 metadata is at end of message metadata-end
✔ 1:8 PR-URL is valid. pr-url
✔ 0:0 reviewers are valid reviewers
✖ 0:0 Commit must have a "Signed-off-by" trailer signed-off-by
✔ 0:0 valid subsystems subsystem
✔ 0:0 Title is formatted correctly. title-format
⚠ 0:50 Title should be <= 50 columns. title-length

ℹ Please fix the commit message and try again.
Please manually ammend the commit message, by running
git commit --amend
Once commit message is fixed, finish the landing command running
git node land --continue

https://github.com/nodejs/node/actions/runs/26114797253

aduh95 · 2026-05-19T18:30:54Z

Landed in b1387e6

nodejs-github-bot added the needs-ci PRs that need a full CI run. label Apr 19, 2026

watilde force-pushed the fixes-memory-sourcemap branch from 3b8cc82 to 73ffd8aCompare April 19, 2026 10:40

watilde changed the title ~~perf: use Object.freeze to avoid defensive cloning in SourceMap~~lib: use Object.freeze to avoid defensive cloning in SourceMapApr 19, 2026

legendecas added semver-major PRs that contain breaking changes and should be released in the next major version. source maps Issues and PRs related to source map support. labels Apr 20, 2026

legendecas reviewed Apr 20, 2026
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legendecas reviewed Apr 22, 2026
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Comment threaddoc/api/module.md

watilde force-pushed the fixes-memory-sourcemap branch from bd11c1e to f5cc42fCompare April 23, 2026 10:36

watilde added 2 commits April 23, 2026 20:03

lib: use Object.freeze to avoid defensive cloning in SourceMap
7b33dfd

doc: clarify sourceMap.payload behavior and immutability
f493f69

watilde force-pushed the fixes-memory-sourcemap branch from f5cc42f to f493f69Compare April 23, 2026 11:04

legendecas added the commit-queue-squash Add this label to instruct the Commit Queue to squash all the PR commits into the first one. label Apr 23, 2026

doc: add change metadata for validator message
d3e4534
Co-authored-by: Chengzhong Wu <legendecas@gmail.com>

watilde added the request-ci Add this label to start a Jenkins CI on a PR. label Apr 23, 2026

doc: fix unclosed YAML comment in sourceMap.payload
673e0a2

watilde removed needs-ci PRs that need a full CI run. request-ci Add this label to start a Jenkins CI on a PR. labels Apr 25, 2026

legendecas approved these changes Apr 25, 2026
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legendecas added the author ready PRs that have at least one approval, no pending requests for changes, and a CI started. label Apr 27, 2026

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aduh95 merged commit b1387e6 into nodejs:mainMay 19, 2026
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watilde deleted the fixes-memory-sourcemap branch May 20, 2026 04:34

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lib: use Object.freeze to avoid defensive cloning in SourceMap - #62830

lib: use Object.freeze to avoid defensive cloning in SourceMap#62830
aduh95 merged 4 commits into
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PR-URL: #62830
Reviewed-By: Chengzhong Wu <legendecas@gmail.com>
Reviewed-By: Yagiz Nizipli <yagiz@nizipli.com>

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PR-URL: #62830 Reviewed-By: Chengzhong Wu <legendecas@gmail.com> Reviewed-By: Yagiz Nizipli <yagiz@nizipli.com>

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PR-URL: #62830
Reviewed-By: Chengzhong Wu <legendecas@gmail.com>
Reviewed-By: Yagiz Nizipli <yagiz@nizipli.com>