perf(router-core): skip impossible JSON parses during search parsing

[Sheraff]

Summary

• apply the existing jsonStart fast path to parseSearchWith when using JSON.parse
• preserve custom parser behavior and cover both paths with unit tests
• add default search parsing benchmark scenarios and a patch changeset

Testing

• CI=1 NX_DAEMON=false pnpm nx run @tanstack/router-core:test:unit --outputStyle=stream --skipRemoteCache -- tests/searchParams.test.ts
• CI=1 NX_DAEMON=false pnpm nx run @tanstack/router-core:test:types --outputStyle=stream --skipRemoteCache
• CI=1 NX_DAEMON=false pnpm nx run @tanstack/router-core:test:eslint --outputStyle=stream --skipRemoteCache
• CI=1 NX_DAEMON=false pnpm nx run @tanstack/router-core:test:unit --outputStyle=stream --skipRemoteCache -- bench tests/searchParams.bench.ts --run

Summary by CodeRabbit

• Bug Fixes

  • Improved search-parameter parsing by skipping values that cannot be valid JSON.
  • Preserved existing parsing behavior and silent error handling for eligible values.

• Performance

  • Reduced unnecessary JSON parsing during search-parameter processing.

• Tests

  • Added coverage for custom parsing, decoded parameters, invalid JSON values, and parsing performance.

[nx-cloud]

View your CI Pipeline Execution ↗ for commit bfb5233

Command	Status	Duration	Result
nx affected --targets=test:eslint,test:unit,tes...	✅ Succeeded	11m 58s	View ↗
nx run-many --target=build --exclude=examples/*...	✅ Succeeded	2m 6s	View ↗

---

☁️ Nx Cloud last updated this comment at 2026-08-08 18:40:15 UTC

[github-actions]

🚀 Changeset Version Preview

2 package(s) bumped directly, 21 bumped as dependents.

🟩 Patch bumps

Package	Version	Reason
@tanstack/router-core	1.171.19 → 1.171.20	Changeset
@tanstack/start-client-core	1.170.19 → 1.170.20	Changeset
@tanstack/react-router	1.170.23 → 1.170.24	Dependent
@tanstack/react-start	1.168.40 → 1.168.41	Dependent
@tanstack/react-start-client	1.168.21 → 1.168.22	Dependent
@tanstack/react-start-rsc	0.1.39 → 0.1.40	Dependent
@tanstack/react-start-server	1.167.28 → 1.167.29	Dependent
@tanstack/router-cli	1.167.25 → 1.167.26	Dependent
@tanstack/router-generator	1.167.25 → 1.167.26	Dependent
@tanstack/router-plugin	1.168.27 → 1.168.28	Dependent
@tanstack/router-vite-plugin	1.167.27 → 1.167.28	Dependent
@tanstack/solid-router	1.170.22 → 1.170.23	Dependent
@tanstack/solid-start	1.168.39 → 1.168.40	Dependent
@tanstack/solid-start-client	1.168.21 → 1.168.22	Dependent
@tanstack/solid-start-server	1.167.28 → 1.167.29	Dependent
@tanstack/start-plugin-core	1.171.31 → 1.171.32	Dependent
@tanstack/start-server-core	1.169.23 → 1.169.24	Dependent
@tanstack/start-static-server-functions	1.167.24 → 1.167.25	Dependent
@tanstack/start-storage-context	1.167.21 → 1.167.22	Dependent
@tanstack/vue-router	1.170.21 → 1.170.22	Dependent
@tanstack/vue-start	1.168.38 → 1.168.39	Dependent
@tanstack/vue-start-client	1.167.24 → 1.167.25	Dependent
@tanstack/vue-start-server	1.167.28 → 1.167.29	Dependent

[coderabbitai]

No actionable comments were generated in the recent review. 🎉

ℹ️ Recent review info

⚙️ Run configuration

Configuration used: defaults

Review profile: CHILL

Plan: Pro Plus

Run ID: 25e0496d-f38b-4880-b2e3-8de1cae4b5bf

📥 Commits

Reviewing files that changed from the base of the PR and between 44a8c3e and bfb5233.

📒 Files selected for processing (4)

• .changeset/fast-search-parsing.md
• packages/router-core/src/searchParams.ts
• packages/router-core/tests/searchParams.bench.ts
• packages/router-core/tests/searchParams.test.ts

---

📝 Walkthrough

Walkthrough

parseSearchWith now skips native JSON.parse attempts for values that cannot begin valid JSON. Tests cover custom parsers and skipped calls. Benchmarks measure parsing across several search-parameter value sets. A patch Changeset documents the behavior.

Changes

Search parameter parsing

Layer / File(s)	Summary
Parser optimization and validation packages/router-core/src/searchParams.ts, packages/router-core/tests/searchParams.test.ts, .changeset/fast-search-parsing.md	parseSearchWith detects native JSON.parse and skips values that cannot begin valid JSON. Tests cover custom parser output, decoded values, and skipped JSON.parse calls.
Parsing benchmark coverage packages/router-core/tests/searchParams.bench.ts	Benchmarks parse ordinary, JSON-initial, JSON-compatible, and mixed serialized search values. Round-trip assertions validate the prepared fixtures.

Estimated code review effort: 2 (Simple) | ~15 minutes

Possibly related PRs

• TanStack/router#8006: Both changes update parseSearchWith to skip impossible JSON.parse attempts and add related tests and Changesets.

🚥 Pre-merge checks | ✅ 5

✅ Passed checks (5 passed)

Check name	Status	Explanation
Description Check	✅ Passed	Check skipped - CodeRabbit’s high-level summary is enabled.
Title check	✅ Passed	The title clearly and concisely describes the main performance change in search parsing.
Docstring Coverage	✅ Passed	No functions found in the changed files to evaluate docstring coverage. Skipping docstring coverage check.
Linked Issues check	✅ Passed	Check skipped because no linked issues were found for this pull request.
Out of Scope Changes check	✅ Passed	Check skipped because no linked issues were found for this pull request.

✨ Finishing Touches

📝 Generate docstrings

• Create stacked PR
• Commit on current branch

🧪 Generate unit tests (beta)

• Create PR with unit tests
• Commit unit tests in branch perf/router-core-search-parse-fast-path

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[github-actions]

Bundle Size Benchmarks

• Commit: 6f3a5ba67da0
• Measured at: 2026-08-08T18:29:25.678Z
• Baseline source: history:44a8c3e1d2af
• Dashboard: bundle-size history

The following scenarios have bundle-size changes compared with the baseline:

Scenario	Current (gzip)	Delta vs baseline	Initial gzip	Raw	Brotli	Trend
react-router.minimal	83.93 KiB	+18 B (+0.02%)	83.80 KiB	262.72 KiB	73.03 KiB	███████▁▁▁▁▁
react-router.full	87.45 KiB	+18 B (+0.02%)	87.31 KiB	274.43 KiB	76.16 KiB	███████▁▁▁▁▁
solid-router.minimal	33.26 KiB	+20 B (+0.06%)	33.13 KiB	96.55 KiB	30.05 KiB	███████▁▁▁▁▁
solid-router.full	38.08 KiB	+17 B (+0.04%)	37.96 KiB	111.19 KiB	34.30 KiB	███████▁▁▁▁▁
vue-router.minimal	49.54 KiB	+20 B (+0.04%)	49.42 KiB	138.30 KiB	44.75 KiB	███████▁▁▁▁▁
vue-router.full	55.12 KiB	+16 B (+0.03%)	55.00 KiB	156.47 KiB	49.64 KiB	███████▁▁▁▁▁
react-start.minimal	96.77 KiB	+16 B (+0.02%)	96.64 KiB	304.93 KiB	83.86 KiB	███████▁▁▁▁▁
react-start.deferred-hydration	97.50 KiB	+16 B (+0.02%)	96.66 KiB	306.29 KiB	84.51 KiB	███████▁▁▁▁▁
react-start.full	99.94 KiB	+20 B (+0.02%)	99.80 KiB	314.65 KiB	86.61 KiB	███████▁▁▁▁▁
react-start.rsbuild.minimal	100.08 KiB	+18 B (+0.02%)	99.91 KiB	315.48 KiB	86.35 KiB	▁▄▄▃▃▄▄▄▄▆▇█
react-start.rsbuild.minimal-iife	100.49 KiB	+19 B (+0.02%)	100.32 KiB	316.42 KiB	86.61 KiB	▁▄▄▃▃▄▄▄▄▆▇█
react-start.rsbuild.full	103.41 KiB	+17 B (+0.02%)	103.24 KiB	325.57 KiB	89.02 KiB	▁▃▃▃▃▄▄▄▄▆▇█
solid-start.minimal	46.03 KiB	+16 B (+0.03%)	45.90 KiB	137.61 KiB	40.94 KiB	███████▁▁▁▁▁
solid-start.deferred-hydration	49.10 KiB	+15 B (+0.03%)	45.96 KiB	145.07 KiB	43.73 KiB	███████▁▁▁▁▁
solid-start.full	51.11 KiB	+17 B (+0.03%)	50.98 KiB	153.00 KiB	45.31 KiB	███████▁▁▁▁▁
vue-start.minimal	65.56 KiB	+14 B (+0.02%)	65.44 KiB	189.12 KiB	58.36 KiB	███████▁▁▁▁▁
vue-start.full	69.39 KiB	+19 B (+0.03%)	69.26 KiB	201.40 KiB	61.67 KiB	███████▁▁▁▁▁

Current gzip tracks all emitted client JS chunks. Initial gzip tracks only the entry/import graph. Trend sparkline is historical current gzip ending with this PR measurement; lower is better.

[pkg-pr-new]

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commit: bfb5233

[codspeed-hq]

Merging this PR will degrade performance by 10.71%

⚠️ Different runtime environments detected

Some benchmarks with significant performance changes were compared across different runtime environments,
which may affect the accuracy of the results.

Open the report in CodSpeed to investigate

⚡ 3 improved benchmarks
❌ 5 regressed benchmarks
✅ 172 untouched benchmarks

Warning

Please fix the performance issues or acknowledge them on CodSpeed.

Performance Changes

	Mode	Benchmark	BASE	HEAD	Efficiency
❌	Memory	mem server error-paths unmatched (react)	272.3 KB	849.3 KB	-67.93%
❌	Memory	mem client unique-location-churn (solid)	352.4 KB	457.4 KB	-22.96%
❌	Memory	mem client navigation-churn (solid)	575 KB	629 KB	-8.58%
❌	Memory	mem client unique-location-churn (vue)	1.2 MB	1.3 MB	-6.16%
❌	Memory	mem server server-fn-churn (vue)	263.2 KB	274.8 KB	-4.21%
⚡	Memory	mem server error-paths not-found (solid)	728.6 KB	417 KB	+74.72%
⚡	Memory	mem client preload-churn (vue)	805.5 KB	736.6 KB	+9.35%
⚡	Memory	mem server error-paths not-found (react)	260.8 KB	250.3 KB	+4.18%

Tip

Investigate this regression by commenting @codspeedbot fix this regression on this PR, or directly use the CodSpeed MCP with your agent.

---

_{Comparing perf/router-core-search-parse-fast-path (bfb5233) with main (44a8c3e)}