Add support for headingProperties

Closes GH-20.
Closes GH-21.

Co-authored-by: Chris Weber <chris963@gmail.com>

lib/index.js

@@ -37,6 +37,8 @@
  * @property {Readonly<ElementContent> | ReadonlyArray<ElementContent> | Build | null | undefined} [group]
  *   Content to wrap the heading and link with, if `behavior` is `'after'` or
  *   `'before'` (optional).
+ * @property {Readonly<Properties> | BuildProperties | null | undefined} [headingProperties]
+ *   Extra properties to set on the heading (optional).
  * @property {Readonly<Properties> | BuildProperties | null | undefined} [properties]
  *   Extra properties to set on the link when injecting (default:
  *   `{ariaHidden: true, tabIndex: -1}` if `'append'` or `'prepend'`, otherwise
@@ -97,7 +99,8 @@ const emptyOptions = {}
  */
 export default function rehypeAutolinkHeadings(options) {
   const settings = options || emptyOptions
-  let props = settings.properties
+  let properties = settings.properties
+  const headingOroperties = settings.headingProperties
   const behavior = settings.behavior || 'prepend'
   const content = settings.content
   const group = settings.group
@@ -113,8 +116,8 @@ export default function rehypeAutolinkHeadings(options) {
   } else {
     method = inject
 
-    if (!props) {
-      props = {ariaHidden: 'true', tabIndex: -1}
+    if (!properties) {
+      properties = {ariaHidden: 'true', tabIndex: -1}
     }
   }
 
@@ -129,6 +132,7 @@ export default function rehypeAutolinkHeadings(options) {
   return function (tree) {
     visit(tree, 'element', function (node, index, parent) {
       if (headingRank(node) && node.properties.id && is(node, index, parent)) {
+        Object.assign(node.properties, toProperties(headingOroperties, node))
         return method(node, index, parent)
       }
     })
@@ -138,7 +142,7 @@ export default function rehypeAutolinkHeadings(options) {
   function inject(node) {
     const children = toChildren(content || contentDefaults, node)
     node.children[behavior === 'prepend' ? 'unshift' : 'push'](
-      create(node, toProperties(props, node), children)
+      create(node, toProperties(properties, node), children)
     )
 
     return [SKIP]
@@ -150,7 +154,7 @@ export default function rehypeAutolinkHeadings(options) {
     if (typeof index !== 'number' || !parent) return
 
     const children = toChildren(content || contentDefaults, node)
-    const link = create(node, toProperties(props, node), children)
+    const link = create(node, toProperties(properties, node), children)
     let nodes = behavior === 'before' ? [link, node] : [node, link]
 
     if (group) {
@@ -184,7 +188,7 @@ export default function rehypeAutolinkHeadings(options) {
     node.children = [
       create(
         node,
-        toProperties(props, node),
+        toProperties(properties, node),
         Array.isArray(after) ? [...before, ...after] : [...before, after]
       )
     ]
@@ -213,18 +217,18 @@ function clone(thing) {
  *
  * @param {Readonly<Element>} node
  *   Related heading.
- * @param {Properties | undefined} props
+ * @param {Properties | undefined} properties
  *   Properties to set on the link.
  * @param {Array<ElementContent>} children
  *   Content.
  * @returns {Element}
  *   Link.
  */
-function create(node, props, children) {
+function create(node, properties, children) {
   return {
     type: 'element',
     tagName: 'a',
-    properties: {...props, href: '#' + node.properties.id},
+    properties: {...properties, href: '#' + node.properties.id},
     children
   }
 }

readme.md

@@ -217,6 +217,9 @@ Configuration (TypeScript type).
     optional)
     — content to wrap the heading and link with, if `behavior` is `'after'` or
     `'before'`
+*   `headingProperties` ([`BuildProperties`][api-build-properties] or
+    [`Properties`][hast-properties], optional)
+    — extra properties to set on the heading
 *   `properties` ([`BuildProperties`][api-build-properties] or
     [`Properties`][hast-properties], default:
     `{ariaHidden: true, tabIndex: -1}` if `'append'` or `'prepend'`, otherwise

test/fixtures/heading-properties/config.json

@@ -0,0 +1,6 @@
+{
+  "headingProperties": {
+    "className": ["foo", "bar", "baz"],
+    "dataQux": "quux"
+  }
+}

test/fixtures/heading-properties/input.html

@@ -0,0 +1 @@
+<h1 id="foo">Bar</h1>

test/fixtures/heading-properties/output.html

@@ -0,0 +1 @@
+<h1 id="foo" class="foo bar baz" data-qux="quux"><a aria-hidden="true" tabindex="-1" href="#foo"><span class="icon icon-link"></span></a>Bar</h1>

test/index.js

@@ -30,31 +30,9 @@ test('rehypeAutolinkHeadings', async function (t) {
           assert.equal(node.properties.id, 'a')
           return {type: 'element', tagName: 'div', properties: {}, children: []}
         },
-        properties(node) {
+        headingProperties(node) {
           assert.equal(node.properties.id, 'a')
-          return {dataX: 'y'}
-        }
-      })
-      .process('<h1 id=a>b</h1>')
-
-    assert.deepEqual(
-      String(file),
-      '<div><h1 id="a">b</h1><a data-x="y" href="#a"><i></i></a></div>'
-    )
-  })
-
-  await t.test('should support functions', async function () {
-    const file = await rehype()
-      .data('settings', {fragment: true})
-      .use(rehypeAutolinkHeadings, {
-        behavior: 'after',
-        content(node) {
-          assert.equal(node.properties.id, 'a')
-          return {type: 'element', tagName: 'i', properties: {}, children: []}
-        },
-        group(node) {
-          assert.equal(node.properties.id, 'a')
-          return {type: 'element', tagName: 'div', properties: {}, children: []}
+          return {dataA: 'b'}
         },
         properties(node) {
           assert.equal(node.properties.id, 'a')
@@ -65,7 +43,7 @@ test('rehypeAutolinkHeadings', async function (t) {
 
     assert.deepEqual(
       String(file),
-      '<div><h1 id="a">b</h1><a data-x="y" href="#a"><i></i></a></div>'
+      '<div><h1 id="a" data-a="b">b</h1><a data-x="y" href="#a"><i></i></a></div>'
     )
   })