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Add graphemeLength util for Bluesky post limit
author
Jeremy Herve
date
(Jun 12, 2026, 5:40 PM +0200)
commit
7ad86cf7
7ad86cf719afc42ce1450275412b359b016ca978
parent
ec9a60f6
ec9a60f645dc7bcfec8ea97c6318dd12c170fde2
+35
+22
src/lib/publish/grapheme.test.ts
+22
src/lib/publish/grapheme.test.ts
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import { describe, expect, it } from 'vitest';
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import { graphemeLength } from './grapheme';
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describe( 'graphemeLength', () => {
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it( 'counts ASCII characters one-for-one', () => {
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expect( graphemeLength( 'hello' ) ).toBe( 5 );
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} );
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it( 'counts an emoji as a single grapheme', () => {
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// "👍" is 2 UTF-16 code units / 4 UTF-8 bytes but one grapheme.
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expect( graphemeLength( '👍' ) ).toBe( 1 );
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} );
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it( 'counts a multi-codepoint emoji cluster as one grapheme', () => {
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// Family emoji = several codepoints joined by ZWJ, still one grapheme.
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expect( graphemeLength( '👨👩👧' ) ).toBe( 1 );
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} );
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it( 'returns 0 for the empty string', () => {
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expect( graphemeLength( '' ) ).toBe( 0 );
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} );
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} );
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src/lib/publish/grapheme.ts
+13
src/lib/publish/grapheme.ts
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/**
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* Count graphemes (user-perceived characters) the way Bluesky counts toward its
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* 300-character post limit — emoji and ZWJ clusters count as one, not as their
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* UTF-16 length or byte length.
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*/
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export function graphemeLength( text: string ): number {
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const segmenter = new Intl.Segmenter( undefined, { granularity: 'grapheme' } );
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let count = 0;
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for ( const _segment of segmenter.segment( text ) ) {
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count++;
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}
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return count;
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}