49 lines
1 KiB
JavaScript
49 lines
1 KiB
JavaScript
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/**
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* @typedef {import('hast').Root} Root
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*/
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/**
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* @typedef Options
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* Configuration (optional).
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* @property {string} [prefix='']
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* Prefix to add in front of `id`s (default: `''`).
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*/
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import GithubSlugger from 'github-slugger'
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import {headingRank} from 'hast-util-heading-rank'
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import {toString} from 'hast-util-to-string'
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import {visit} from 'unist-util-visit'
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/** @type {Options} */
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const emptyOptions = {}
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const slugs = new GithubSlugger()
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/**
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* Add `id`s to headings.
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*
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* @param {Options | null | undefined} [options]
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* Configuration (optional).
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* @returns
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* Transform.
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*/
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export default function rehypeSlug(options) {
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const settings = options || emptyOptions
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const prefix = settings.prefix || ''
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/**
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* @param {Root} tree
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* Tree.
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* @returns {undefined}
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* Nothing.
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*/
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return function (tree) {
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slugs.reset()
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visit(tree, 'element', function (node) {
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if (headingRank(node) && !node.properties.id) {
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node.properties.id = prefix + slugs.slug(toString(node))
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}
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})
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}
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}
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