A calm place to write long-form, and publish it to the open social web.
skypress.blog/
Add deriveExcerpt helper for description fallback
author
Jeremy Herve
date
(Jun 9, 2026, 9:18 PM +0200)
commit
8948da43
8948da437dd21d703c8af9ca85f586effb7a43a2
parent
6803d3a1
6803d3a15472a7fc2f408803115eae51bb245bc6
+49
+32
src/lib/publish/excerpt.test.ts
+32
src/lib/publish/excerpt.test.ts
···
1
+
import { describe, expect, it } from 'vitest';
2
+
import { deriveExcerpt } from './excerpt';
3
+
4
+
describe( 'deriveExcerpt', () => {
5
+
it( 'returns empty string for empty or whitespace-only input', () => {
6
+
expect( deriveExcerpt( '' ) ).toBe( '' );
7
+
expect( deriveExcerpt( ' \n\t ' ) ).toBe( '' );
8
+
} );
9
+
10
+
it( 'returns short text unchanged, with no ellipsis', () => {
11
+
expect( deriveExcerpt( 'A short lede.' ) ).toBe( 'A short lede.' );
12
+
} );
13
+
14
+
it( 'collapses internal whitespace and newlines to single spaces', () => {
15
+
expect( deriveExcerpt( 'one\n\ntwo three' ) ).toBe( 'one two three' );
16
+
} );
17
+
18
+
it( 'truncates long text on a word boundary with a trailing ellipsis', () => {
19
+
const long = 'word '.repeat( 100 ).trim(); // 499 chars, all word boundaries
20
+
const result = deriveExcerpt( long );
21
+
expect( result.endsWith( '…' ) ).toBe( true );
22
+
// Body (sans ellipsis) stays within the limit and never splits a word.
23
+
const body = result.slice( 0, -1 );
24
+
expect( body.length ).toBeLessThanOrEqual( 200 );
25
+
expect( body.endsWith( 'word' ) ).toBe( true );
26
+
expect( body.endsWith( ' ' ) ).toBe( false );
27
+
} );
28
+
29
+
it( 'honours a custom maxChars and cuts at the last space within it', () => {
30
+
expect( deriveExcerpt( 'alpha beta gamma', 10 ) ).toBe( 'alpha…' );
31
+
} );
32
+
} );
+17
src/lib/publish/excerpt.ts
+17
src/lib/publish/excerpt.ts
···
1
+
/**
2
+
* A brief plain-text excerpt for a document/card description (the og:description fallback).
3
+
* Collapses runs of whitespace to single spaces, cuts on a word boundary at or before
4
+
* `maxChars`, and appends an ellipsis when it had to truncate. Returns '' for empty or
5
+
* whitespace-only input. Pure + dependency-free (no `@wordpress/*`, no network) so it is
6
+
* safe in BOTH the server reader and the browser publisher (AGENTS.md §3).
7
+
*/
8
+
export function deriveExcerpt( text: string, maxChars = 200 ): string {
9
+
const normalized = text.replace( /\s+/g, ' ' ).trim();
10
+
if ( normalized.length <= maxChars ) {
11
+
return normalized;
12
+
}
13
+
const slice = normalized.slice( 0, maxChars );
14
+
const lastSpace = slice.lastIndexOf( ' ' );
15
+
const cut = lastSpace > 0 ? slice.slice( 0, lastSpace ) : slice;
16
+
return `${ cut.trimEnd() }…`;
17
+
}