Refactor code-style

package.json

@@ -28,16 +28,13 @@
     "rehype-parse": "^9.0.0",
     "rehype-stringify": "^10.0.0",
     "remark-cli": "^11.0.0",
-    "remark-html": "^15.0.0",
     "remark-parse": "^11.0.0",
     "remark-preset-wooorm": "^9.0.0",
     "remark-rehype": "^10.0.0",
     "remark-stringify": "^11.0.0",
-    "to-vfile": "^8.0.0",
     "type-coverage": "^2.0.0",
     "typescript": "^5.0.0",
     "unified": "^11.0.0",
-    "unist-builder": "^4.0.0",
     "unist-util-remove-position": "^5.0.0",
     "xo": "^0.56.0"
   },

packages/rehype-katex/index.js

@@ -1,33 +1,50 @@
 /**
+ * @typedef {import('hast').ElementContent} ElementContent
  * @typedef {import('hast').Root} Root
+ *
  * @typedef {import('katex').KatexOptions} Options
+ *
+ * @typedef {import('vfile').VFile} VFile
  */
 
+import {fromHtmlIsomorphic} from 'hast-util-from-html-isomorphic'
+import {toText} from 'hast-util-to-text'
 import katex from 'katex'
 import {visit} from 'unist-util-visit'
-import {toText} from 'hast-util-to-text'
-import {fromHtmlIsomorphic} from 'hast-util-from-html-isomorphic'
-
-const assign = Object.assign
 
-const source = 'rehype-katex'
+/** @type {Readonly<Options>} */
+const emptyOptions = {}
+/** @type {ReadonlyArray<unknown>} */
+const emptyClasses = []
 
 /**
  * Plugin to transform `<span class=math-inline>` and `<div class=math-display>`
  * with KaTeX.
  *
- * @type {import('unified').Plugin<[Options?]|void[], Root>}
+ * @param {Readonly<Options> | null | undefined} [options]
+ *   Configuration (optional).
+ * @returns
+ *   Transform.
  */
 export default function rehypeKatex(options) {
-  const settings = options || {}
+  const settings = options || emptyOptions
   const throwOnError = settings.throwOnError || false
 
-  return (tree, file) => {
-    visit(tree, 'element', (element) => {
-      const classes =
-        element.properties && Array.isArray(element.properties.className)
-          ? element.properties.className
-          : []
+  /**
+   * Transform.
+   *
+   * @param {Root} tree
+   *   Tree.
+   * @param {VFile} file
+   *   File.
+   * @returns {undefined}
+   *   Nothing.
+   */
+  return function (tree, file) {
+    visit(tree, 'element', function (element) {
+      const classes = Array.isArray(element.properties.className)
+        ? element.properties.className
+        : emptyClasses
       const inline = classes.includes('math-inline')
       const displayMode = classes.includes('math-display')
 
@@ -41,50 +58,49 @@ export default function rehypeKatex(options) {
       let result
 
       try {
-        result = katex.renderToString(
-          value,
-          assign({}, settings, {displayMode, throwOnError: true})
-        )
-      } catch (error_) {
-        const error = /** @type {Error} */ (error_)
+        result = katex.renderToString(value, {
+          ...settings,
+          displayMode,
+          throwOnError: true
+        })
+      } catch (error) {
+        const exception = /** @type {Error} */ (error)
         const fn = throwOnError ? 'fail' : 'message'
-        const origin = [source, error.name.toLowerCase()].join(':')
+        const origin = ['rehype-katex', exception.name.toLowerCase()].join(':')
 
-        file[fn](error.message, element.position, origin)
+        file[fn](exception.message, element.position, origin)
 
         // KaTeX can handle `ParseError` itself, but not others.
         // Generate similar markup if this is an other error.
         // See: <https://github.com/KaTeX/KaTeX/blob/5dc7af0/docs/error.md>.
-        if (error.name !== 'ParseError') {
+        if (exception.name !== 'ParseError') {
           element.children = [
             {
               type: 'element',
               tagName: 'span',
               properties: {
                 className: ['katex-error'],
-                title: String(error),
-                style: 'color:' + (settings.errorColor || '#cc0000')
+                style: 'color:' + (settings.errorColor || '#cc0000'),
+                title: String(error)
               },
               children: [{type: 'text', value}]
             }
           ]
           return
         }
 
-        result = katex.renderToString(
-          value,
-          assign({}, settings, {
-            displayMode,
-            throwOnError: false,
-            strict: 'ignore'
-          })
-        )
+        result = katex.renderToString(value, {
+          ...settings,
+          displayMode,
+          strict: 'ignore',
+          throwOnError: false
+        })
       }
 
       const root = fromHtmlIsomorphic(result, {fragment: true})
-      // To do: cast content.
-      // @ts-expect-error: assume no `doctypes` in KaTeX result.
-      element.children = root.children
+      // Cast because there will not be `doctypes` in KaTeX result.
+      const content = /** @type {Array<ElementContent>} */ (root.children)
+      element.children = content
     })
   }
 }

packages/rehype-katex/package.json

@@ -43,7 +43,8 @@
     "hast-util-from-html-isomorphic": "^2.0.0",
     "hast-util-to-text": "^4.0.0",
     "katex": "^0.16.0",
-    "unist-util-visit": "^5.0.0"
+    "unist-util-visit": "^5.0.0",
+    "vfile": "^6.0.0"
   },
   "scripts": {
     "test-api": "node --conditions development test.js",