Refactor code-style

*   Add more docs to JSDoc
*   Add support for `null` in input of API types

lib/contents.js

@@ -1,18 +1,20 @@
 /**
- * @typedef {import('mdast').Root|import('mdast').Content} Node
  * @typedef {import('mdast').List} List
  * @typedef {import('mdast').ListItem} ListItem
  * @typedef {import('mdast').PhrasingContent} PhrasingContent
  * @typedef {import('mdast').StaticPhrasingContent} StaticPhrasingContent
  * @typedef {import('./search.js').SearchEntry} SearchEntry
- *
+ */
+
+/**
  * @typedef ContentsOptions
- * @property {boolean} [tight=false]
+ *   Build configuration.
+ * @property {boolean | null | undefined} [tight=false]
  *   Whether to compile list-items tightly.
- * @property {boolean} [ordered=false]
+ * @property {boolean | null | undefined} [ordered=false]
  *   Whether to compile list-items as an ordered list, otherwise they are
  *   unordered.
- * @property {string|null} [prefix=null]
+ * @property {string | null | undefined} [prefix=null]
  *   Add a prefix to links to headings in the table of contents.
  *   Useful for example when later going from mdast to hast and sanitizing with
  *   `hast-util-sanitize`.
@@ -61,11 +63,12 @@ export function contents(map, settings) {
  * Insert an entry into `parent`.
  *
  * @param {SearchEntry} entry
- * @param {List|ListItem} parent
+ * @param {List | ListItem} parent
  * @param {ContentsOptions} settings
  */
 function insert(entry, parent, settings) {
   let index = -1
+  const tail = parent.children[parent.children.length - 1]
 
   if (parent.type === 'list') {
     if (entry.depth === 1) {
@@ -87,7 +90,8 @@ function insert(entry, parent, settings) {
         ]
       })
     } else if (parent.children.length > 0) {
-      insert(entry, parent.children[parent.children.length - 1], settings)
+      const tail = parent.children[parent.children.length - 1]
+      insert(entry, tail, settings)
     } else {
       /** @type {ListItem} */
       const item = {type: 'listItem', spread: false, children: []}
@@ -96,17 +100,9 @@ function insert(entry, parent, settings) {
     }
   }
   // List item
-  else if (
-    parent.children[parent.children.length - 1] &&
-    parent.children[parent.children.length - 1].type === 'list'
-  ) {
+  else if (tail && tail.type === 'list') {
     entry.depth--
-    insert(
-      entry,
-      // @ts-expect-error It’s a `list`, we just checked.
-      parent.children[parent.children.length - 1],
-      settings
-    )
+    insert(entry, tail, settings)
   } else {
     /** @type {List} */
     const item = {
@@ -154,16 +150,18 @@ function all(nodes) {
 
 /**
  * @param {PhrasingContent} node
- * @returns {StaticPhrasingContent|Array<StaticPhrasingContent>}
+ * @returns {StaticPhrasingContent | Array<StaticPhrasingContent>}
  */
 function one(node) {
+  if (node.type === 'footnoteReference') {
+    return []
+  }
+
   if (
     node.type === 'link' ||
     node.type === 'linkReference' ||
-    node.type === 'footnote' ||
-    node.type === 'footnoteReference'
+    node.type === 'footnote'
   ) {
-    // @ts-expect-error Looks like a parent.
     return all(node.children)
   }
 

lib/index.js

@@ -1,18 +1,28 @@
 /**
- * @typedef {import('mdast').Root|import('mdast').Content} Node
+ * @typedef {import('mdast').Root} Root
+ * @typedef {import('mdast').Content} Content
  * @typedef {import('mdast').List} List
  * @typedef {import('./search.js').SearchOptions} SearchOptions
  * @typedef {import('./contents.js').ContentsOptions} ContentsOptions
+ */
+
+/**
+ * @typedef {Root | Content} Node
  * @typedef {SearchOptions & ContentsOptions & ExtraOptions} Options
  *
  * @typedef ExtraOptions
- * @property {string} [heading]
+ *   Extra configuration fields.
+ * @property {string | null | undefined} [heading]
  *   Heading to look for, wrapped in `new RegExp('^(' + value + ')$', 'i')`.
  *
  * @typedef Result
- * @property {number|null} index
- * @property {number|null} endIndex
- * @property {List|null} map
+ *   Results.
+ * @property {number | null} index
+ *   Where the contents section starts, if looking for a heading.
+ * @property {number | null} endIndex
+ *   Where the contents section ends, if looking for a heading.
+ * @property {List | null} map
+ *   Built table of contents (`List`).
  */
 
 import {search} from './search.js'
@@ -32,14 +42,17 @@ import {toExpression} from './to-expression.js'
  * Only top-level headings (those not in blockquotes or lists), are used.
  * This default behavior can be changed by passing `options.parents`.
  *
- * @param {Node} node
- * @param {Options} [options]
+ * @param {Node} tree
+ *   Tree to search and generate from.
+ * @param {Options | null | undefined} [options]
+ *   Configuration.
  * @returns {Result}
+ *   Results.
  */
-export function toc(node, options) {
+export function toc(tree, options) {
   const settings = options || {}
-  const heading = settings.heading ? toExpression(settings.heading) : null
-  const result = search(node, heading, settings)
+  const heading = settings.heading ? toExpression(settings.heading) : undefined
+  const result = search(tree, heading, settings)
 
   return {
     index: heading ? result.index : null,

lib/search.js

@@ -1,35 +1,53 @@
 /**
- * @typedef {import('mdast').Root|import('mdast').Content} Node
+ * @typedef {import('mdast').Root} Root
+ * @typedef {import('mdast').Content} Content
  * @typedef {import('mdast').Heading} Heading
  * @typedef {import('mdast').PhrasingContent} PhrasingContent
- * @typedef {string} IsType
- * @typedef {Record<string, unknown>} IsProps
- * @typedef {import('unist-util-is').TestFunctionAnything} IsTestFunctionAnything
+ * @typedef {import('unist-util-is').Test} Test
+ */
+
+/**
+ * @typedef {Root | Content} Node
+ * @typedef {Heading['depth']} Rank
  *
+ */
+
+/**
  * @typedef SearchOptions
- * @property {string} [skip]
+ *   Search configuration.
+ * @property {string | null | undefined} [skip]
  *   Headings to skip, wrapped in `new RegExp('^(' + value + ')$', 'i')`.
  *   Any heading matching this expression will not be present in the table of
  *   contents.
- * @property {IsType|IsProps|IsTestFunctionAnything|Array<IsType|IsProps|IsTestFunctionAnything>} [parents]
+ * @property {Test} [parents]
  *   Allow headings to be children of certain node types (default: the to `toc`
  *   given `tree`, to only allow top-level headings).
+ *
  *   Internally, uses `unist-util-is` to check, so `parents` can be any
  *   `is`-compatible test.
- * @property {Heading['depth']} [maxDepth=6]
+ * @property {Rank | null | undefined} [maxDepth=6]
  *   Maximum heading depth to include in the table of contents.
+ *
  *   This is inclusive: when set to `3`, level three headings are included
  *   (those with three hashes, `###`).
  *
  * @typedef SearchEntry
- * @property {Heading['depth']} depth
- * @property {Array<PhrasingContent>} children
+ *   Entry.
  * @property {string} id
+ *   ID of entry.
+ * @property {Array<PhrasingContent>} children
+ *   Contents of entry.
+ * @property {Rank} depth
+ *   Rank of entry.
  *
  * @typedef SearchResult
+ *   Results.
  * @property {number} index
+ *   Where the contents section starts, if looking for a heading.
  * @property {number} endIndex
+ *   Where the contents section ends, if looking for a heading.
  * @property {Array<SearchEntry>} map
+ *   List of entries.
  */
 
 import Slugger from 'github-slugger'
@@ -44,20 +62,20 @@ const slugs = new Slugger()
  * Search a node for a toc.
  *
  * @param {Node} root
- * @param {RegExp|null} expression
+ * @param {RegExp | undefined} expression
  * @param {SearchOptions} settings
  * @returns {SearchResult}
  */
 export function search(root, expression, settings) {
-  const skip = settings.skip && toExpression(settings.skip)
+  const skip = settings.skip ? toExpression(settings.skip) : undefined
   const parents = convert(settings.parents || ((d) => d === root))
   /** @type {Array<SearchEntry>} */
   const map = []
-  /** @type {number|undefined} */
+  /** @type {number | undefined} */
   let index
-  /** @type {number} */
+  /** @type {number | undefined} */
   let endIndex
-  /** @type {Heading} */
+  /** @type {Heading | undefined} */
   let opening
 
   slugs.reset()
@@ -103,10 +121,10 @@ export function search(root, expression, settings) {
   })
 
   return {
-    index: index || -1,
+    index: index === undefined ? -1 : index,
     // <sindresorhus/eslint-plugin-unicorn#980>
     // @ts-expect-error Looks like a parent.
-    endIndex: index ? endIndex || root.children.length : -1, // eslint-disable-line unicorn/explicit-length-check
+    endIndex: index === undefined ? -1 : endIndex || root.children.length, // eslint-disable-line unicorn/explicit-length-check
     map
   }
 }