Investigate migrating from eslint to oxlint

[antonis]

The JS SDK is working on it in getsentry/sentry-javascript#19134

If we decide to proceed with this we should also close #5600

[linear]

RN-479

[antonis]

Analysis: Oxlint Migration Feasibility

TL;DR

✅ User Impact: Zero - this is purely an internal development tool change
⚠️ Complexity: Medium (3/5) - easier than ESLint 9, but has timing dependencies
🚧 Main Blocker: Coordination with sentry-javascript's shared config migration
🚀 Benefits: 12x faster linting, 2.4x faster CI (based on JS SDK benchmarks)

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Migration Difficulty: Medium

Advantages over staying on ESLint 8:

• Simpler config format than ESLint 9's flat config
• Fewer config files to migrate (~6 vs 61 in sentry-javascript)
• Most custom Sentry rules are already disabled in RN SDK
• Dramatic performance improvements

Challenges:

1. React Native Plugin Support: eslint-plugin-react-native requires oxlint's experimental JS plugin system

   {
     "jsPlugins": ["eslint-plugin-react-native"],
     "rules": {
       "react-native/no-unused-styles": "error"
     }
   }

   ⚠️ JS plugins are experimental and may reduce performance benefits

2. Shared Config Dependency: Depends on @sentry-internal/eslint-config-sdk migration status

   • Need to coordinate with sentry-javascript timeline
   • Alternative: maintain separate ESLint/oxlint config versions (maintenance overhead)

3. Known Rule Gaps (from sentry-javascript#19134):

   • Import sorting (use prettier/oxfmt instead)
   • TypeScript member-ordering and naming-convention
   • 4 custom Sentry rules (mostly disabled in RN anyway)

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Blockers Assessment

Blocker	Severity	Mitigation
React Native plugin support	Medium	Use experimental JS plugins (works, but not ideal)
Timing dependency on JS SDK	High	Coordinate migration or fork shared configs
Custom Sentry rules	Low	Already disabled in RN SDK

Most Critical Question: What's the plan for @sentry-internal/eslint-config-sdk?

• Will it maintain parallel ESLint/oxlint versions?
• Or fully migrate to oxlint?
• Timeline?

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Comparison: ESLint 9 (#5600) vs Oxlint

Aspect	ESLint 9	Oxlint
Complexity	⭐⭐⭐⭐ (4/5)	⭐⭐⭐ (3/5)
Config Migration	Flat config (breaking change)	Simple .oxlintrc.json
Dependencies	typescript-eslint v5→v8	Timing dependency on JS SDK
Independence	✅ Can migrate now	❌ Needs coordination
Performance	No improvement	🚀 12x faster
CI Time	Same	🚀 2.4x faster
Ecosystem Support	✅ Mature	⚠️ RN plugin experimental
Migration Tooling	@eslint/migrate-config	Manual (but simpler)

ESLint 9 Breaking Changes:

• Mandatory flat config (no more .eslintrc.*)
• Node.js 18.18.0+ required
• Complete config rewrite needed
• All plugins must be ESLint 9 compatible

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Recommendations

Option 1: Migrate to Oxlint (Recommended if coordinated)

• ✅ Best long-term performance
• ✅ Aligns with sentry-javascript
• ❌ Requires coordination
• Action: Wait for sentry-javascript#19134 to land, then follow their pattern

Option 2: Migrate to ESLint 9 first

• ✅ Independent timeline
• ✅ Resolves Bump to ESLint 9 #5600 and unblocks chore(deps-dev): bump eslint from 8.57.1 to 9.26.0 #5594
• ✅ Keeps oxlint migration option open
• ❌ More complex migration
• ❌ May need to migrate again later to oxlint
• Action: Proceed with ESLint 9 now, evaluate oxlint in 6 months

Option 3: Stay on ESLint 8

• ✅ No migration work
• ❌ EOL concerns (ESLint 9 is current)
• ❌ Blocks future improvements
• ❌ Diverges from JS SDK
• Not recommended

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Decision Points

Before deciding, clarify with the JS SDK team:

1. Timeline: When will sentry-javascript#19134 merge?
2. Shared configs: Will @sentry-internal/eslint-config-sdk support both ESLint and oxlint, or migrate fully?
3. Support plan: Who maintains React Native-specific oxlint config?

My recommendation:

• If JS SDK is migrating soon (< 1 month) → Wait and migrate together to oxlint
• If JS SDK timeline is uncertain → Migrate to ESLint 9 now for independence
• The 12x performance gain and CI speedup make oxlint worth the coordination effort if feasible

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Related Issues

• Bump to ESLint 9 #5600 - Bump to ESLint 9
• chore(deps-dev): bump eslint from 8.57.1 to 9.26.0 #5594 - ESLint 8→9 PR (currently blocked)
• chore: migrate to oxlint sentry-javascript#19134 - JS SDK oxlint migration (draft)

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Sources:

• Oxlint JS Plugins Documentation
• ESLint 9 Migration Guide
• Oxlint 1.0 Release
• sentry-javascript oxlint PR

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Generated by Claude