[Archibald1948]

Summary

I ran the examples in docs/reference and docs/compat/reference against the current code and found 13 whose documented result does not match what the code returns. This fixes all of them in all four languages, bundled into one pull request as the contributing guide asks.

No shipped code changes. For every es-toolkit/compat example below I also ran lodash, and es-toolkit/compat already matches it — the code is right, the docs were not.

How I found them

I extracted every typescript block, executed each statement that is followed by // Returns:, // =>, // Result: or a same-line value comment, and deep-compared the value with the documented one. Of 2,125 checked statements, 12 did not match and 23 threw. The 13 issues below are the real ones; the rest came from running blocks in isolation (a block that uses users defined in an earlier block, a placeholder iteratee, the browser document).

Fixes

Page	Example	Documented	Actual	Fix
take	take([1, 2, 3])	[1]	[1, 2, 3]	removed the "if you omit count" section
takeRight	takeRight([1, 2, 3])	[3]	[1, 2, 3]	removed the "if you omit count" section
compat unzipWith	(a, b) => a + b over three groups	['abc', 'xyz']	['ab', 'xy']	iteratee takes all three: (a, b, c) => a + b + c
compat nthArg	arrays.map(nthArg(1))	[2, 5, 8]	[0, 1, 2]	arrays.map(array => nthArg(1)(...array))
compat rearg	rearg(fn, [1, [2, 0]], 3)	['b', 'c', 'a', 'd']	['b', undefined, 'd', 'd']	rearg(fn, [1, 2], [0, 3])
compat spread	spread(greet, 1) with greet(greeting, names)	'Hello, Alice and Bob!'	TypeError: names.join is not a function	greet(greeting, ...names)
compat mapValues	(value, index) => value + index on [10, 20, 30]	{ '0': 10, '1': 21, '2': 32 }	{ '0': '100', '1': '201', '2': '302' }	value + Number(index)
compat update	second call in the same block	c: 13	c: 16	corrected the result
compat updateWith	second call in the same block	c: 13	c: 19	corrected the result
compat fromPairs	fromPairs('invalid')	{}	{ i: undefined, n: undefined, … }	removed the line
compat invokeMap	invokeMap(['a', 'b', 'c'], String.prototype.toUpperCase)	only pseudocode	['A', 'B', 'C']	added the actual result
compat range	range(0, 1, 0.2)	[0, 0.2, 0.4, 0.6, 0.8]	[0, 0.2, 0.4, 0.6000000000000001, 0.8]	corrected the result
compat rangeRight	rangeRight(0, 1, 0.2)	[0.8, 0.6, 0.4, 0.2, 0]	[0.8, 0.6000000000000001, 0.4, 0.2, 0]	corrected the result

A few of these deserve a word of explanation.

take / takeRight. The page said that omitting count takes one element. That is lodash's behaviour (and es-toolkit/compat's), but the main take requires the argument and simply slices:

export function take<T>(arr: readonly T[], count: number): T[] {
  return arr.slice(0, count);
}

take([1, 2, 3]); // [1, 2, 3] — and a type error, since `count` is required

So I removed the section rather than documenting a call the signature does not allow.

unzipWith, nthArg, rearg, spread, mapValues. Here the documented result matched what the example was trying to show, but the code did not produce it. I kept the intended result and fixed the code instead, since changing only the comment would have documented a pitfall:

// unzipWith passes one argument per group, so a two-parameter iteratee drops the third
unzipWith([['a', 'x'], ['b', 'y'], ['c', 'z']], (a, b, c) => a + b + c);
// => ['abc', 'xyz']

// Array#map calls the function with (value, index, array), so nthArg(1) picked the index
arrays.map(array => nthArg(1)(...array));
// => [2, 5, 8]

// rearg flattens its index arguments only one level deep
rearg(fn, [1, 2], [0, 3])('a', 'b', 'c', 'd');
// => ['b', 'c', 'a', 'd']

// spread(fn, 1) spreads the array at position 1 into separate arguments
function greet(greeting, ...names) {
  return `${greeting}, ${names.join(' and ')}!`;
}

// mapValues passes object keys, which are strings even for arrays
mapValues([10, 20, 30], (value, index) => value + Number(index));
// => { '0': 10, '1': 21, '2': 32 }

update / updateWith. Both blocks call the function twice on the same object, and the second comment showed the result as if the first call had not run. I corrected the number to what you get running the block top to bottom.

After the change, re-running the check leaves only the isolation artifacts described above, plus the invokeMap pseudocode line, which is intentional and is now followed by the actual result. Every edit touches the same code lines in en, ko, ja and zh_hans, and prettier --check passes on all 52 files.

🤖 Generated with Claude Code

https://claude.ai/code/session_0129BhQdChg7wJry7bWvRHHm

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Project	Deployment	Actions	Updated
es-toolkit	Ready	Preview	Sep 19, 2026 8:24am UTC

[Copilot]

🟡 Changes recommended

The PR still contains a duplicated invokeMap result line and take/takeRight docs continue to describe count as optional/defaulted in a way that contradicts the main entrypoint API.

Get a fresh assessment by requesting another Copilot review.

Pull request overview

This PR updates documentation examples (across English/Korean/Japanese/Simplified Chinese) so that the documented outputs match what es-toolkit / es-toolkit/compat actually returns, without changing shipped code.

Changes:

• Removed incorrect “omit count” sections from main take / takeRight reference docs.
• Corrected multiple compat examples to align with actual runtime behavior (e.g., unzipWith, nthArg, rearg, spread, mapValues).
• Corrected several compat documented results to match real outputs (e.g., update, updateWith, range, rangeRight, invokeMap) across all 4 languages.

File summaries

File	Description
docs/reference/array/take.md	Removes incorrect omit-count example
docs/reference/array/takeRight.md	Removes incorrect omit-count example
docs/ko/reference/array/take.md	Removes incorrect omit-count example (KO)
docs/ko/reference/array/takeRight.md	Removes incorrect omit-count example (KO)
docs/ja/reference/array/take.md	Removes incorrect omit-count example (JA)
docs/ja/reference/array/takeRight.md	Removes incorrect omit-count example (JA)
docs/zh_hans/reference/array/take.md	Removes incorrect omit-count example (ZH)
docs/zh_hans/reference/array/takeRight.md	Removes incorrect omit-count example (ZH)
docs/compat/reference/array/unzipWith.md	Fixes iteratee arity to match actual arguments
docs/ko/compat/reference/array/unzipWith.md	Fixes iteratee arity (KO)
docs/ja/compat/reference/array/unzipWith.md	Fixes iteratee arity (JA)
docs/zh_hans/compat/reference/array/unzipWith.md	Fixes iteratee arity (ZH)
docs/compat/reference/function/nthArg.md	Fixes map usage to avoid passing index into nthArg(1)
docs/ko/compat/reference/function/nthArg.md	Fixes map usage (KO)
docs/ja/compat/reference/function/nthArg.md	Fixes map usage (JA)
docs/zh_hans/compat/reference/function/nthArg.md	Fixes map usage (ZH)
docs/compat/reference/function/rearg.md	Fixes indices example to reflect actual flattening behavior
docs/ko/compat/reference/function/rearg.md	Fixes indices example (KO)
docs/ja/compat/reference/function/rearg.md	Fixes indices example (JA)
docs/zh_hans/compat/reference/function/rearg.md	Fixes indices example (ZH)
docs/compat/reference/function/spread.md	Fixes example function signature to match spread call pattern
docs/ko/compat/reference/function/spread.md	Fixes example function signature (KO)
docs/ja/compat/reference/function/spread.md	Fixes example function signature (JA)
docs/zh_hans/compat/reference/function/spread.md	Fixes example function signature (ZH)
docs/compat/reference/object/mapValues.md	Fixes array-key handling (Number(index))
docs/ko/compat/reference/object/mapValues.md	Fixes array-key handling (KO)
docs/ja/compat/reference/object/mapValues.md	Fixes array-key handling (JA)
docs/zh_hans/compat/reference/object/mapValues.md	Fixes array-key handling (ZH)
docs/compat/reference/object/update.md	Corrects second-call result to reflect prior mutation
docs/ko/compat/reference/object/update.md	Corrects second-call result (KO)
docs/ja/compat/reference/object/update.md	Corrects second-call result (JA)
docs/zh_hans/compat/reference/object/update.md	Corrects second-call result (ZH)
docs/compat/reference/object/updateWith.md	Corrects second-call result to reflect prior mutation
docs/ko/compat/reference/object/updateWith.md	Corrects second-call result (KO)
docs/ja/compat/reference/object/updateWith.md	Corrects second-call result (JA)
docs/zh_hans/compat/reference/object/updateWith.md	Corrects second-call result (ZH)
docs/compat/reference/object/fromPairs.md	Removes invalid fromPairs('invalid') example line
docs/ko/compat/reference/object/fromPairs.md	Removes invalid example line (KO)
docs/ja/compat/reference/object/fromPairs.md	Removes invalid example line (JA)
docs/zh_hans/compat/reference/object/fromPairs.md	Removes invalid example line (ZH)
docs/compat/reference/array/invokeMap.md	Adds concrete output for function-reference example
docs/ko/compat/reference/array/invokeMap.md	Adds concrete output (KO)
docs/ja/compat/reference/array/invokeMap.md	Adds concrete output (JA)
docs/zh_hans/compat/reference/array/invokeMap.md	Adds concrete output (ZH)
docs/compat/reference/math/range.md	Corrects floating-point output example
docs/ko/compat/reference/math/range.md	Corrects floating-point output example (KO)
docs/ja/compat/reference/math/range.md	Corrects floating-point output example (JA)
docs/zh_hans/compat/reference/math/range.md	Corrects floating-point output example (ZH)
docs/compat/reference/math/rangeRight.md	Corrects floating-point output example
docs/ko/compat/reference/math/rangeRight.md	Corrects floating-point output example (KO)
docs/ja/compat/reference/math/rangeRight.md	Corrects floating-point output example (JA)
docs/zh_hans/compat/reference/math/rangeRight.md	Corrects floating-point output example (ZH)

Review details

• Files reviewed: 52/52 changed files
• Comments generated: 16
• Review effort level: Lite

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