refactor: replace for-in loops with Object.entries and enable guard-for-in

[dinwwwh]

Summary

Refactored all for-in loops throughout the codebase to use Object.entries() for more explicit and safer object iteration. This change improves code clarity and enables stricter linting rules.

Key Changes

• aws-lambda/headers.ts: Converted 4 for-in loops to Object.entries() when iterating over headers and multiValueHeaders
• aws-lambda/url.ts: Converted 2 for-in loops to Object.entries() when iterating over query parameters
• shared/object.ts: Simplified hasAnyDefinedValue() to use Object.values() instead of for-in with key lookup
• core/utils.ts: Converted for-in loop in mergeStandardHeaders() to Object.entries(), eliminating redundant variable assignment
• fastify/response.ts: Converted for-in loop to Object.entries() when setting response headers
• node/response.ts: Converted for-in loop to Object.entries() when setting response headers
• eslint.config.js: Enabled guard-for-in ESLint rule to prevent future for-in usage without explicit checks

Implementation Details

• All conversions maintain identical functionality while improving code readability
• Destructuring syntax for (const [key, value] of Object.entries(...)) makes variable sources explicit
• Eliminates potential issues with inherited properties from prototype chain
• The new ESLint rule ensures this pattern is enforced going forward

https://claude.ai/code/session_01JkQExPkUtiRfuLoFyXpqGD

[pkg-pr-new]

• @standard-server/hono-node-playground
• @standard-server/node-http-playground

@standard-server/aws-lambda

npm i https://pkg.pr.new/@standard-server/aws-lambda@90

@standard-server/core

npm i https://pkg.pr.new/@standard-server/core@90

@standard-server/fastify

npm i https://pkg.pr.new/@standard-server/fastify@90

@standard-server/fetch

npm i https://pkg.pr.new/@standard-server/fetch@90

@standard-server/node

npm i https://pkg.pr.new/@standard-server/node@90

@standard-server/peer

npm i https://pkg.pr.new/@standard-server/peer@90

@standard-server/shared

npm i https://pkg.pr.new/@standard-server/shared@90

commit: 624382e

[codspeed]

Merging this PR will not alter performance

✅ 26 untouched benchmarks
⏩ 108 skipped benchmarks¹

---

_{Comparing claude/exciting-turing-yddy8o (624382e) with main (57b5cb3)}

Footnotes

1. 108 benchmarks were skipped, so the baseline results were used instead. If they were deleted from the codebase, click here and archive them to remove them from the performance reports. ↩

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.

📢 Thoughts on this report? Let us know!

[pullfrog]

✅ No new issues found.

Reviewed changes — full PR (#90), all 7 files and the single commit 1c8326d.

• eslint.config.js — enables guard-for-in as error; pnpm lint is clean, and a repo-wide grep confirms no for...in loops remain, so the rule cannot trip CI on existing code.
• packages/aws-lambda/src/headers.ts — toStandardHeaders (2), getEventHeader (2), and toLambdaHeaders (1) switch to Object.entries destructuring.
• packages/aws-lambda/src/url.ts — toStandardUrl's two loops destructure [key, values], dropping the repeated index lookup.
• packages/core/src/utils.ts — mergeStandardHeaders pulls bValue straight from the entries tuple; Object.hasOwn still gates inherited keys.
• packages/fastify/src/response.ts / packages/node/src/response.ts — response header loops converted, undefined filtering unchanged.
• packages/shared/src/object.ts — hasAnyDefinedValue uses Object.values, matching the JSDoc ("own property with a defined value").

The refactor is behaviorally neutral for the objects these paths actually see (plain literals, JSON.parse results, and null-prototype Object.create(null) maps). The one real semantic shift — inherited enumerable properties are no longer visited — is the PR's stated goal and, given the Object.hasOwn guard in mergeStandardHeaders and the own-property intent of hasAnyDefinedValue, is a strict improvement. Verified locally: pnpm lint passes and the 324 tests in aws-lambda/core/shared/node/fastify pass.

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[pullfrog]

✅ No new issues found.

Reviewed changes — new head 624382e since the prior review.

The diff for 624382e is byte-for-byte identical to 1c8326d (verified by comparing the two formatted diffs); the only change is the commit subject. No new code to review — the prior approval stands.

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