[Patrick-SCH03]

Summary

Compat deburr applies NFD normalization to the entire string, while Lodash replaces letters in U+00C0–U+017F and removes combining marks without normalizing the string. This decomposes Hangul syllables and alters Cyrillic and Vietnamese text, also affecting the six compat case-conversion functions. The following calls compile in strict mode with @types/lodash.

import { camelCase, deburr, kebabCase } from 'es-toolkit/compat';

kebabCase('한국어') === '한국어';
// lodash:           true  (3 characters)
// es-toolkit/compat: false (8 decomposed Hangul jamo, NFD)

kebabCase('Мой край');
// lodash:           'мой-край'
// es-toolkit/compat: 'мои-краи'

deburr('йогурт');
// lodash:           'йогурт'
// es-toolkit/compat: 'иогурт'

camelCase('Tiếng Việt');
// lodash:           'tiếngViệt'
// es-toolkit/compat: 'tiengViet'

Changes

• Replace compat's delegation with a 192-entry lookup table generated once at module initialization using the existing main implementation. Leave the main es-toolkit implementation unchanged.
• Use an ASCII fast path and a single loop to replace Latin letters and remove combining marks, without calling normalize() on each invocation.
• Fix camelCase, kebabCase, lowerCase, snakeCase, startCase, and upperCase through their existing compat deburr imports.
• Add regression tests in deburr.spec.ts, kebabCase.spec.ts, and camelCase.spec.ts that fail on main and pass on this branch.
• Update the compat camelCase bundle-size snapshot from 2,161 to 2,471 bytes (+310 bytes).

Comparing all 194,560 non-surrogate code points in U+0000–U+2FFFF against Lodash found zero mismatches on this branch, down from 13,088 on main.

Unlike the NFC recomposition approach in #1905, this preserves characters whose combining marks would otherwise be removed.

Benchmark results

Measured on Windows with Node.js 22, alternating main and this branch in the same benchmark file; values are ops/sec (higher is better). Equivalent cases were run with vitest bench using direct src/compat imports because the benchmarks workspace failed with ERR_UNSUPPORTED_ESM_URL_SCHEME.

Case	main	This branch
deburr('déjà vu, Ærøskøbing')	1,962,075	5,777,000
deburr('hello world foo bar') (ASCII)	2,882,578	10,898,472
kebabCase('Foo Bar déjà vu')	550,893	696,225

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Project	Deployment	Actions	Updated
es-toolkit	Ready	Preview	Sep 27, 2026 8:12am UTC