Add options for setting a prefix

rehypejs · Oct 5, 2022 · 82d837c · 82d837c
1 parent 31483c0
commit 82d837c
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Showing 2 changed files with 45 additions and 5 deletions.
diff --git a/index.js b/index.js
@@ -1,5 +1,10 @@
 /**
  * @typedef {import('hast').Root} Root
+ * @typedef {string} Prefix
+ * @typedef Options
+ *   Configuration.
+ * @property {Prefix} [prefix='']
+ * 
  */
 
 import Slugger from 'github-slugger'
@@ -12,16 +17,17 @@ const slugs = new Slugger()
 
 /**
  * Plugin to add `id`s to headings.
- *
- * @type {import('unified').Plugin<Array<void>, Root>}
+ * @type {import('unified').Plugin<[Options?]|Array<void>, Root>}
  */
-export default function rehypeSlug() {
+export default function rehypeSlug(options = {}) {
+  let prefix = options.prefix || '';
+
   return (tree) => {
     slugs.reset()
 
     visit(tree, 'element', (node) => {
       if (headingRank(node) && node.properties && !hasProperty(node, 'id')) {
-        node.properties.id = slugs.slug(toString(node))
+        node.properties.id = `${prefix}${slugs.slug(toString(node))}`
       }
     })
   }

diff --git a/test.js b/test.js
@@ -3,7 +3,7 @@ import {rehype} from 'rehype'
 import rehypeSlug from './index.js'
 
 test('rehypeSlug', (t) => {
-  t.plan(2)
+  t.plan(4)
 
   rehype()
     .data('settings', {fragment: true})
@@ -38,4 +38,38 @@ test('rehypeSlug', (t) => {
         )
       }
     )
+
+  rehype()
+    .data('settings', {fragment: true})
+    .use(rehypeSlug, { prefix: 'test-'})
+    .process(
+      [
+        '<section>',
+        '  <h1>Lorem ipsum 😪</h1>',
+        '  <h2>dolor—sit—amet</h2>',
+        '  <h3>consectetur &amp; adipisicing</h3>',
+        '  <h4>elit</h4>',
+        '  <h5>elit</h5>',
+        '  <p>sed</p>',
+        '</section>'
+      ].join('\n'),
+      (error, file) => {
+        t.ifErr(error, 'shouldn’t throw')
+
+        t.equal(
+          String(file),
+          [
+            '<section>',
+            '  <h1 id="test-lorem-ipsum-">Lorem ipsum 😪</h1>',
+            '  <h2 id="test-dolorsitamet">dolor—sit—amet</h2>',
+            '  <h3 id="test-consectetur--adipisicing">consectetur &#x26; adipisicing</h3>',
+            '  <h4 id="test-elit">elit</h4>',
+            '  <h5 id="test-elit-1">elit</h5>',
+            '  <p>sed</p>',
+            '</section>'
+          ].join('\n'),
+          'should match'
+        )
+      }
+    )
 })