Reading time

Inject an estimated reading-time as an MDX named export available alongside frontmatter.

The readingTime feature walks the parsed markdown AST, counts words, and injects export const readingTimeMinutes = N; into the compiled MDX module. The export is then available as entry.readingTimeMinutes in any TSX page that imports the collection.

Enable

// zfb.config.ts
export default defineConfig({
  markdown: {
    features: {
      readingTime: true,
    },
  },
});

To customise the words-per-minute rate:

// zfb.config.ts
export default defineConfig({
  markdown: {
    features: {
      readingTime: { wpm: 250 },
    },
  },
});

Usage in a TSX page

// src/pages/blog/[...slug].tsx
const { readingTimeMinutes, ...rest } = await entry.render();

// readingTimeMinutes is a number — use it in your layout:
<p>{readingTimeMinutes} min read</p>

Word counting formula

The plugin combines two passes:

1. Latin-script text — the text is split on whitespace; each token counts as one word. Punctuation attached to a token (e.g. don't, hello-world) counts as one word, consistent with remark-reading-time.

2. CJK characters — each character in the following Unicode blocks counts as one word, because CJK text does not use spaces between words:

   • CJK Unified Ideographs + Extension A (U+3400–U+9FFF)
   • CJK Compatibility Ideographs (U+F900–U+FAFF)
   • Hiragana (U+3040–U+309F)
   • Katakana (U+30A0–U+30FF)
   • Hangul Syllables (U+AC00–U+D7AF)

   Source: remark-reading-time — “It also uses CJK character count for languages that don’t use spaces between words.”

The total word count (Latin tokens + CJK characters) is divided by the WPM value, ceiling-rounded to the nearest whole minute, with a minimum of 1.

Code blocks are excluded

Fenced code blocks and inline code are not counted. A document whose code block contains hundreds of lines will not be over-estimated based on code content.

Examples

Notes

• The minimum returned value is always 1 minute, regardless of article length.
• Reading time is computed against the prose content only — headings, paragraphs, lists, blockquotes, and emphasis all contribute; code blocks, raw HTML, and math blocks do not.
• The export is injected at the mdast phase (before HTML/JSX conversion) so it is always consistent with the document content.