Refactor code-style

*   Add more docs to JSDoc

Author: wooorm

lib/index.js

@@ -1,19 +1,33 @@
 /**
- * @typedef {Extract<import('mdast').Root|import('mdast').Content, import('unist').Parent>} Parent
+ * @typedef {import('mdast').Content} Content
  * @typedef {import('mdast').ListItem} ListItem
  * @typedef {import('mdast').Paragraph} Paragraph
- * @typedef {import('mdast').BlockContent} BlockContent
+ * @typedef {import('mdast').Parent} Parent
+ * @typedef {import('mdast').Root} Root
  * @typedef {import('mdast-util-from-markdown').CompileContext} CompileContext
  * @typedef {import('mdast-util-from-markdown').Extension} FromMarkdownExtension
  * @typedef {import('mdast-util-from-markdown').Handle} FromMarkdownHandle
  * @typedef {import('mdast-util-to-markdown').Options} ToMarkdownExtension
  * @typedef {import('mdast-util-to-markdown').Handle} ToMarkdownHandle
  */
 
+/**
+ * @typedef {Extract<Root | Content, Parent>} Parents
+ */
+
 import {listItem} from 'mdast-util-to-markdown/lib/handle/list-item.js'
 import {track} from 'mdast-util-to-markdown/lib/util/track.js'
 
-/** @type {FromMarkdownExtension} */
+// To do: next major: rename `context` -> `state`, `safeOptions` -> `info`, use
+// `track` from `state`.
+// To do: next major: replace exports with functions.
+// To do: next major: use `defaulthandlers.listItem`.
+
+/**
+ * Extension for `mdast-util-from-markdown` to enable GFM task list items.
+ *
+ * @type {FromMarkdownExtension}
+ */
 export const gfmTaskListItemFromMarkdown = {
   exit: {
     taskListCheckValueChecked: exitCheck,
@@ -22,7 +36,11 @@ export const gfmTaskListItemFromMarkdown = {
   }
 }
 
-/** @type {ToMarkdownExtension} */
+/**
+ * Extension for `mdast-util-to-markdown` to enable GFM task list items.
+ *
+ * @type {ToMarkdownExtension}
+ */
 export const gfmTaskListItemToMarkdown = {
   unsafe: [{atBreak: true, character: '-', after: '[:|-]'}],
   handlers: {listItem: listItemWithTaskListItem}
@@ -43,43 +61,45 @@ function exitCheck(token) {
  * @type {FromMarkdownHandle}
  */
 function exitParagraphWithTaskListItem(token) {
-  const parent = /** @type {Parent} */ (this.stack[this.stack.length - 2])
-  const node = /** @type {Paragraph} */ (this.stack[this.stack.length - 1])
-  const siblings = parent.children
-  const head = node.children[0]
-  let index = -1
-  /** @type {Paragraph|undefined} */
-  let firstParaghraph
+  const parent = /** @type {Parents} */ (this.stack[this.stack.length - 2])
 
   if (
     parent &&
     parent.type === 'listItem' &&
-    typeof parent.checked === 'boolean' &&
-    head &&
-    head.type === 'text'
+    typeof parent.checked === 'boolean'
   ) {
-    while (++index < siblings.length) {
-      const sibling = siblings[index]
-      if (sibling.type === 'paragraph') {
-        firstParaghraph = sibling
-        break
+    const node = /** @type {Paragraph} */ (this.stack[this.stack.length - 1])
+    const head = node.children[0]
+
+    if (head && head.type === 'text') {
+      const siblings = parent.children
+      let index = -1
+      /** @type {Paragraph | undefined} */
+      let firstParaghraph
+
+      while (++index < siblings.length) {
+        const sibling = siblings[index]
+        if (sibling.type === 'paragraph') {
+          firstParaghraph = sibling
+          break
+        }
       }
-    }
 
-    if (firstParaghraph === node) {
-      // Must start with a space or a tab.
-      head.value = head.value.slice(1)
-
-      if (head.value.length === 0) {
-        node.children.shift()
-      } else if (
-        node.position &&
-        head.position &&
-        typeof head.position.start.offset === 'number'
-      ) {
-        head.position.start.column++
-        head.position.start.offset++
-        node.position.start = Object.assign({}, head.position.start)
+      if (firstParaghraph === node) {
+        // Must start with a space or a tab.
+        head.value = head.value.slice(1)
+
+        if (head.value.length === 0) {
+          node.children.shift()
+        } else if (
+          node.position &&
+          head.position &&
+          typeof head.position.start.offset === 'number'
+        ) {
+          head.position.start.column++
+          head.position.start.offset++
+          node.position.start = Object.assign({}, head.position.start)
+        }
       }
     }
   }