blog/src/plugins/remark-reading-time.mjs

import { toString } from 'mdast-util-to-string'
import getReadingTime from 'reading-time'

export function remarkReadingTime() {
  return (tree, { data }) => {
    const textOnPage = toString(tree)
    const readingTime = getReadingTime(textOnPage)
    data.astro.frontmatter.minutes = Math.max(
      1,
      Math.round(readingTime.minutes),
    )
  }
}