feat(object): implement sortKeys

[guesung]

Summary

• Implement sortKeys utility that creates a new object with keys sorted alphabetically
• Supports optional custom compare function for different sorting behavior
• Based on sort-keys by Sindre Sorhus, with a simpler API following es-toolkit's design principles

Changes

• src/object/sortKeys.ts — Implementation
• src/object/sortKeys.spec.ts — Tests (7 cases)
• src/object/index.ts — Re-export
• Docs in 4 languages (en, ko, ja, zh_hans)

Test plan

• All 7 unit tests pass (yarn vitest run src/object/sortKeys)
• ESLint: 0 errors
• TypeScript: no new type errors

Closes #1618

[vercel]

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Project	Deployment	Actions	Updated (UTC)
es-toolkit	Ready	Preview, Comment	Mar 31, 2026 6:46am

[codecov-commenter]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 99.97%. Comparing base (cd553ee) to head (7d29d4b).

Additional details and impacted files

@@           Coverage Diff           @@
##             main    #1674   +/-   ##
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  Coverage   99.97%   99.97%           
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  Files         497      498    +1     
  Lines        4662     4669    +7     
  Branches     1348     1348           
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+ Hits         4661     4668    +7     
  Misses          1        1           

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[Copilot]

Pull request overview

Adds a new sortKeys utility to the object module to return a new object whose (string) keys are sorted deterministically (default alphabetical, optionally via a custom comparator), along with unit tests, re-export, and multilingual documentation to expose it as part of the public API surface.

Changes:

• Implement sortKeys in src/object/sortKeys.ts with an optional custom compare function.
• Add vitest coverage for common sorting scenarios in src/object/sortKeys.spec.ts.
• Re-export from src/object/index.ts and add reference docs (en/ko/ja/zh_hans).

Reviewed changes

Copilot reviewed 7 out of 7 changed files in this pull request and generated 6 comments.

Show a summary per file

File	Description
src/object/sortKeys.ts	New implementation of key-sorting object utility.
src/object/sortKeys.spec.ts	New unit tests covering default/custom ordering and immutability.
src/object/index.ts	Re-export sortKeys from the object entrypoint.
docs/reference/object/sortKeys.md	English reference documentation for sortKeys.
docs/ko/reference/object/sortKeys.md	Korean reference documentation for sortKeys.
docs/ja/reference/object/sortKeys.md	Japanese reference documentation for sortKeys.
docs/zh_hans/reference/object/sortKeys.md	Simplified Chinese reference documentation for sortKeys.

---

💡 Add Copilot custom instructions for smarter, more guided reviews. Learn how to get started.

[Copilot]

result[key] = object[key] will trigger the __proto__ setter on normal objects if the input contains an own enumerable "__proto__" key (e.g. from Object.create(null)), which can mutate result's prototype (prototype pollution). Consider skipping unsafe keys (via the existing isUnsafeProperty helper) and/or defining properties with Object.defineProperty (or creating result with a null prototype) so assigning "__proto__" cannot change the prototype chain.

Suggested change

	const key = sortedKeys[i];
	const key = sortedKeys[i];
	// Skip unsafe keys that could lead to prototype pollution.
	if (key === '__proto__' || key === 'constructor' || key === 'prototype') {
	continue;
	}

[Copilot]

There is no test covering objects that contain an own enumerable "__proto__" key. Given other object utilities explicitly guard against unsafe keys, add a test ensuring sortKeys does not mutate the returned object's prototype when sorting such inputs.

[Copilot]

The TypeScript snippet sortKeys(object, compare?) is not valid TypeScript syntax (the ? marker can’t be used in a call expression). Update the snippet to a valid call (e.g. sortKeys(object) and sortKeys(object, compare)).

Suggested change

	const sorted = sortKeys(object, compare?);
	const sorted = sortKeys(object);

[Copilot]

The TypeScript snippet sortKeys(object, compare?) is not valid TypeScript syntax (the ? marker can’t be used in a call expression). Update the snippet to a valid call (e.g. sortKeys(object) and sortKeys(object, compare)).

Suggested change

	const sorted = sortKeys(object, compare?);
	const sorted = sortKeys(object, compare);

[Copilot]

The TypeScript snippet sortKeys(object, compare?) is not valid TypeScript syntax (the ? marker can’t be used in a call expression). Update the snippet to a valid call (e.g. sortKeys(object) and sortKeys(object, compare)).

Suggested change

	const sorted = sortKeys(object, compare?);
	const sorted = sortKeys(object, compare);

[Copilot]

代码片段 sortKeys(object, compare?) 不是合法的 TypeScript 调用写法（? 只能用于类型/参数声明，不能用于调用表达式）。建议改为合法的调用示例（例如 sortKeys(object) / sortKeys(object, compare)）。

Suggested change

	const sorted = sortKeys(object, compare?);
	const sorted = sortKeys(object);