cometkimunicode-segmenter
A lightweight implementation of the Unicode Text Segmentation (UAX #29)
Spec compliant: Up-to-date Unicode data, verified by the official Unicode test suites and fuzzed with the native
Intl.Segmenter, and maintaining 100% test coverage.Excellent compatibility: It works well on older browsers, edge runtimes, React Native (Hermes) and QuickJS.
Zero-dependencies: It doesn't bloat
node_modulesor the network bandwidth. Like a small minimal snippet.Small bundle size: It effectively compresses the Unicode data and provides a bundler-friendly format.
Extremely efficient: It's carefully optimized for runtime performance, making it the fastest one in the ecosystem—outperforming even the built-in
Intl.Segmenter.TypeScript: It's fully type-checked, and provides type definitions and JSDoc.
ESM-first: It primarily supports ES modules, and still supports CommonJS.
[!NOTE] unicode-segmenter is now e18e recommendation!
Unicode® Version
Unicode® 16.0.0
Unicode® Standard Annex #29 - Revision 45 (2024-08-28)
APIs
There are several entries for text segmentation.
unicode-segmenter/grapheme: Segments and counts extended grapheme clustersunicode-segmenter/intl-adapter:Intl.Segmenteradapterunicode-segmenter/intl-polyfill:Intl.Segmenterpolyfill
And extra utilities for combined use cases.
unicode-segmenter/emoji: Matches single codepoint emojisunicode-segmenter/general: Matches single codepoint alphanumericsunicode-segmenter/utils: Some utilities for handling codepoints
Export unicode-segmenter/grapheme
Utilities for text segmentation by extended grapheme cluster rules.
Example: Get grapheme segments
import { graphemeSegments } from 'unicode-segmenter/grapheme';
[...graphemeSegments('a̐éö̲\r\n')];
// 0: { segment: 'a̐', index: 0, input: 'a̐éö̲\r\n' }
// 1: { segment: 'é', index: 2, input: 'a̐éö̲\r\n' }
// 2: { segment: 'ö̲', index: 4, input: 'a̐éö̲\r\n' }
// 3: { segment: '\r\n', index: 7, input: 'a̐éö̲\r\n' }Example: Split graphemes
import { splitGraphemes } from 'unicode-segmenter/grapheme';
[...splitGraphemes('#️⃣*️⃣0️⃣1️⃣2️⃣')];
// 0: #️⃣
// 1: *️⃣
// 2: 0️⃣
// 3: 1️⃣
// 4: 2️⃣Example: Count graphemes
import { countGraphemes } from 'unicode-segmenter/grapheme';
'👋 안녕!'.length;
// => 6
countGraphemes('👋 안녕!');
// => 5
'a̐éö̲'.length;
// => 7
countGraphemes('a̐éö̲');
// => 3[!NOTE]
countGraphemes()is a small wrapper aroundgraphemeSegments().If you need it more than once at a time, consider memoization or use
graphemeSegments()orsplitSegments()once instead.
Example: Build an advanced grapheme matcher
graphemeSegments() exposes some knowledge identified in the middle of the process to support some useful cases.
For example, knowing the Grapheme_Cluster_Break category at the beginning and end of a segment can help approximately infer the applied boundary rule.
import { graphemeSegments, GraphemeCategory } from 'unicode-segmenter/grapheme';
function* matchEmoji(str) {
for (const { segment, _catBegin } of graphemeSegments(input)) {
// `_catBegin` identified as Extended_Pictographic means the segment is emoji
if (_catBegin === GraphemeCategory.Extended_Pictographic) {
yield segment;
}
}
}
[...matchEmoji('1🌷2🎁3💩4😜5👍')]
// 0: 🌷
// 1: 🎁
// 2: 💩
// 3: 😜
// 4: 👍Or build even more advanced one like an Unicode-aware TTY string width utility.
Export unicode-segmenter/intl-adapter
Intl.Segmenter API adapter (only granularity: "grapheme" available yet)
import { Segmenter } from 'unicode-segmenter/intl-adapter';
// Same API with the `Intl.Segmenter`
const segmenter = new Segmenter();Export unicode-segmenter/intl-polyfill
Intl.Segmenter API polyfill (only granularity: "grapheme" available yet)
// Apply polyfill to the `globalThis.Intl` object.
import 'unicode-segmenter/intl-polyfill';
const segmenter = new Intl.Segmenter();Export unicode-segmenter/emoji
Utilities for matching emoji-like characters.
Example: Use Unicode emoji property matches
import {
isEmojiPresentation, // match \p{Emoji_Presentation}
isExtendedPictographic, // match \p{Extended_Pictographic}
} from 'unicode-segmenter/emoji';
isEmojiPresentation('😍'.codePointAt(0));
// => true
isEmojiPresentation('♡'.codePointAt(0));
// => false
isExtendedPictographic('😍'.codePointAt(0));
// => true
isExtendedPictographic('♡'.codePointAt(0));
// => trueExport unicode-segmenter/general
Utilities for matching alphanumeric characters.
Example: Use Unicode general property matchers
import {
isLetter, // match \p{L}
isNumeric, // match \p{N}
isAlphabetic, // match \p{Alphabetic}
isAlphanumeric, // match [\p{N}\p{Alphabetic}]
} from 'unicode-segmenter/general';Export unicode-segmenter/utils
You can access some internal utilities to deal with JavaScript strings.
Example: Handle UTF-16 surrogate pairs
import {
isHighSurrogate,
isLowSurrogate,
surrogatePairToCodePoint,
} from 'unicode-segmenter/utils';
const u32 = '😍';
const hi = u32.charCodeAt(0);
const lo = u32.charCodeAt(1);
if (isHighSurrogate(hi) && isLowSurrogate(lo)) {
const codePoint = surrogatePairToCodePoint(hi, lo);
// => equivalent to u32.codePointAt(0)
}Example: Determine the length of a character
import { isBMP } from 'unicode-segmenter/utils';
const char = '😍'; // .length = 2
const cp = char.codePointAt(0);
char.length === isBMP(cp) ? 1 : 2;
// => trueRuntime Compatibility
unicode-segmenter uses only fundamental features of ES2015, making it compatible with most browsers.
To ensure compatibility, the runtime should support:
If the runtime doesn't support these features, it can easily be fulfilled with tools like Babel.
React Native Support
Since Hermes doesn't support the Intl.Segmenter API yet, unicode-segmenter is a good alternative.
unicode-segmenter is compiled into small & efficient Hermes bytecode than other JavaScript libraries. See the benchmark for details.
Comparison
unicode-segmenter aims to be lighter and faster than alternatives in the ecosystem while fully spec compliant. So the benchmark is tracking several libraries' performance, bundle size, and Unicode version compliance.
unicode-segmenter/grapheme vs
- graphemer@1.4.0 (34.4M+ weekly downloads on NPM)
- grapheme-splitter@1.0.4 (6.3M+ weekly downloads on NPM)
- @formatjs/intl-segmenter@11.7.10 (10K+ weekly downloads on NPM)
- WebAssembly build of unicode-segmentation@1.12.0 with minimum bindings
- Built-in
Intl.SegmenterAPI
JS Bundle Stats
| Name | Unicode® | ESM? | Size | Size (min) | Size (min+gzip) | Size (min+br) |
|---|---|---|---|---|---|---|
unicode-segmenter/grapheme |
16.0.0 | ✔️ | 16,056 | 12,150 | 5,070 | 3,761 |
graphemer |
15.0.0 | ✖️ ️ | 410,435 | 95,104 | 15,752 | 10,660 |
grapheme-splitter |
10.0.0 | ✖️ | 122,252 | 23,680 | 7,852 | 4,841 |
@formatjs/intl-segmenter* |
15.0.0 | ✖️ | 603,285 | 369,560 | 72,218 | 49,416 |
unicode-segmentation* |
16.0.0 | ✔️ | 56,529 | 52,443 | 24,110 | 17,343 |
Intl.Segmenter* |
- | - | 0 | 0 | 0 | 0 |
@formatjs/intl-segmenterhandles grapheme, word, and sentence, but it's not tree-shakable.unicode-segmentationsize contains only minimum WASM binary and its bindings to execute benchmarking. It will increases to expose more features.Intl.Segmenter's Unicode data depends on the host, and may not be up-to-date.Intl.Segmentermay not be available in some old browsers, edge runtimes, or embedded environments.
Hermes Bytecode Stats
| Name | Bytecode size | Bytecode size (gzip)* |
|---|---|---|
unicode-segmenter/grapheme |
22,110 | 11,566 |
graphemer |
133,978 | 31,713 |
grapheme-splitter |
63,835 | 19,137 |
- It would be compressed when included as an app asset.
Runtime Performance
Here is a brief explanation, and you can see archived benchmark results.
Performance in Node.js: unicode-segmenter/grapheme is significantly faster than alternatives.
- 6~15x faster than other JavaScript libraries
- 1.5~3x faster than WASM binding of the Rust's unicode-segmentation
- 1.5~3x faster than built-in
Intl.Segmenter
Performance in Bun: unicode-segmenter/grapheme has almost the same performance as the built-in Intl.Segmenter, with no performance degradation compared to other JavaScript libraries.
Performance in Browsers: The performance in browser environments varies greatly due to differences in browser engines and versions, which makes benchmarking less consistent. Despite these variations, unicode-segmenter/grapheme generally outperforms other JavaScript libraries in most environments.
Performance in React Native: unicode-segmenter/grapheme is significantly faster than alternatives when compiled to Hermes bytecode. It's 3~8x faster than graphemer and 20~26x faster than grapheme-splitter, with the performance gap increasing with input size.
Performance in QuickJS: unicode-segmenter/grapheme is the only usable library in terms of performance.
Instead of trusting these claims, you can try yarn perf:grapheme directly in your environment or build your own benchmark.
Acknowledgments
The Rust Unicode team (@unicode-rs):\ The initial implementation was ported manually from unicode-segmentation library.
Marijn Haverbeke (@marijnh):\ Inspired a technique that can greatly compress Unicode data table from his library.