Add JSDoc based types

lib/index.js

@@ -1,3 +1,14 @@
+/**
+ * @typedef {import('hast').Parent} HastParent
+ * @typedef {import('hast').Root} HastRoot
+ * @typedef {import('hast').DocType} HastDoctype
+ * @typedef {import('hast').Element} HastElement
+ * @typedef {import('hast').Text} HastText
+ * @typedef {import('hast').Comment} HastComment
+ * @typedef {HastParent['children'][number]} HastChild
+ * @typedef {HastChild|HastRoot} HastNode
+ */
+
 import {webNamespaces} from 'web-namespaces'
 import {h, s} from 'hastscript'
 
@@ -8,32 +19,49 @@ const DOCUMENT_NODE = 9
 const DOCUMENT_TYPE_NODE = 10
 const DOCUMENT_FRAGMENT_NODE = 11
 
-function transform(value) {
-  const node = value || {}
-
+/**
+ * @param {Node} node
+ * @returns {HastNode|null}
+ */
+function transform(node) {
   switch (node.nodeType) {
     case ELEMENT_NODE:
+      // @ts-ignore TypeScript is wrong.
       return element(node)
     case DOCUMENT_NODE:
     case DOCUMENT_FRAGMENT_NODE:
+      // @ts-ignore TypeScript is wrong.
       return root(node)
     case TEXT_NODE:
+      // @ts-ignore TypeScript is wrong.
       return text(node)
     case COMMENT_NODE:
+      // @ts-ignore TypeScript is wrong.
       return comment(node)
     case DOCUMENT_TYPE_NODE:
+      // @ts-ignore TypeScript is wrong.
       return doctype(node)
     default:
       return null
   }
 }
 
-// Transform a document.
+/**
+ * Transform a document.
+ *
+ * @param {Document|DocumentFragment} node
+ * @returns {HastRoot}
+ */
 function root(node) {
   return {type: 'root', children: all(node)}
 }
 
-// Transform a doctype.
+/**
+ * Transform a doctype.
+ *
+ * @param {DocumentType} node
+ * @returns {HastDoctype}
+ */
 function doctype(node) {
   return {
     type: 'doctype',
@@ -43,57 +71,82 @@ function doctype(node) {
   }
 }
 
-// Transform text.
+/**
+ * Transform a text.
+ *
+ * @param {Text} node
+ * @returns {HastText}
+ */
 function text(node) {
   return {type: 'text', value: node.nodeValue}
 }
 
-// Transform a comment.
+/**
+ * Transform a comment.
+ *
+ * @param {Comment} node
+ * @returns {HastComment}
+ */
 function comment(node) {
   return {type: 'comment', value: node.nodeValue}
 }
 
-// Transform an element.
+/**
+ * Transform an element.
+ *
+ * @param {Element} node
+ * @returns {HastElement}
+ */
 function element(node) {
   const space = node.namespaceURI
   const fn = space === webNamespaces.svg ? s : h
   const tagName =
     space === webNamespaces.html ? node.tagName.toLowerCase() : node.tagName
+  /** @type {DocumentFragment|Element} */
   const content =
+    // @ts-ignore Types are wrong.
     space === webNamespaces.html && tagName === 'template' ? node.content : node
   const attributes = node.getAttributeNames()
-  const {length} = attributes
+  /** @type {Object.<string, string>} */
   const props = {}
-  let index = 0
+  let index = -1
 
-  while (index < length) {
-    const key = attributes[index]
-    props[key] = node.getAttribute(key)
-    index += 1
+  while (++index < attributes.length) {
+    props[attributes[index]] = node.getAttribute(attributes[index])
   }
 
   return fn(tagName, props, all(content))
 }
 
+/**
+ * Transform an element.
+ *
+ * @param {Document|DocumentFragment|Element} node
+ * @returns {Array.<HastChild>}
+ */
 function all(node) {
   const nodes = node.childNodes
-  const {length} = nodes
+  /** @type {Array.<HastChild>} */
   const children = []
-  let index = 0
+  let index = -1
 
-  while (index < length) {
+  while (++index < nodes.length) {
     const child = transform(nodes[index])
 
     if (child !== null) {
+      // @ts-ignore Assume no document inside document.
       children.push(child)
     }
-
-    index += 1
   }
 
   return children
 }
 
+/**
+ * @param {Node} node
+ * @returns {HastNode}
+ */
 export function fromDom(node) {
-  return transform(node) || {type: 'root', children: []}
+  // @ts-ignore Code can handle empty “node”.
+  return transform(node || {}) || {type: 'root', children: []}
 }

package.json

@@ -28,33 +28,38 @@
   "module": "dist/hast-util-from-dom.mjs",
   "sideEffects": false,
   "type": "module",
+  "types": "index.d.ts",
   "files": [
     "lib/",
+    "index.d.ts",
     "index.js"
   ],
   "dependencies": {
     "hastscript": "^7.0.0",
     "web-namespaces": "^2.0.0"
   },
   "devDependencies": {
-    "@babel/core": "^7.0.0",
-    "@babel/preset-env": "^7.0.0",
-    "@rollup/plugin-babel": "^5.0.0",
+    "@types/jsdom": "^16.0.0",
+    "@types/tape": "^4.0.0",
     "c8": "^7.0.0",
     "glob": "^7.0.0",
-    "jsdom": "^16.5.3",
+    "jsdom": "^16.0.0",
     "prettier": "^2.0.0",
     "remark-cli": "^9.0.0",
     "remark-preset-wooorm": "^8.0.0",
-    "rollup": "^2.0.0",
-    "tape": "^5.2.2",
+    "rimraf": "^3.0.0",
+    "tape": "^5.0.0",
+    "type-coverage": "^2.0.0",
+    "typescript": "^4.0.0",
     "xo": "^0.39.0"
   },
   "scripts": {
+    "prepack": "npm run build && npm run format",
+    "build": "rimraf \"{lib/**,test/**,}*.d.ts\" && tsc && type-coverage",
     "format": "remark . -qfo && prettier . -w --loglevel warn && xo --fix",
     "test-api": "node test/index.js",
     "test-coverage": "c8 --check-coverage --branches 100 --functions 100 --lines 100 --statements 100 --reporter lcov node test/index.js",
-    "test": "npm run format && npm run test-coverage"
+    "test": "npm run build && npm run format && npm run test-coverage"
   },
   "prettier": {
     "tabWidth": 2,
@@ -71,5 +76,10 @@
     "plugins": [
       "preset-wooorm"
     ]
+  },
+  "typeCoverage": {
+    "atLeast": 100,
+    "detail": true,
+    "strict": true
   }
 }

test/index.js

@@ -7,7 +7,7 @@ import glob from 'glob'
 import {JSDOM} from 'jsdom'
 import {fromDom} from '../index.js'
 
-globalThis.window = new JSDOM().window
+const window = new JSDOM().window
 globalThis.document = window.document
 
 test('hast-util-from-dom', (t) => {
@@ -116,6 +116,7 @@ test('hast-util-from-dom', (t) => {
   )
 
   t.deepEqual(
+    // @ts-ignore runtime.
     fromDom(),
     {type: 'root', children: []},
     'should handle a missing DOM tree'
@@ -135,15 +136,16 @@ test('fixtures', (t) => {
 
   t.end()
 
-  function each(fixturePath) {
+  function each(/** @type {string} */ fixturePath) {
     const input = path.join(fixturePath, 'index.html')
     const output = path.join(fixturePath, 'index.json')
-    const fixtureHtml = fs.readFileSync(input)
+    const fixtureHtml = String(fs.readFileSync(input))
     const actual = fromDom(doc(fixtureHtml))
+    /** @type {unknown} */
     let parsedExpected
 
     try {
-      parsedExpected = JSON.parse(fs.readFileSync(output))
+      parsedExpected = JSON.parse(String(fs.readFileSync(output)))
     } catch {
       fs.writeFileSync(output, JSON.stringify(actual, null, 2))
       return
@@ -153,7 +155,7 @@ test('fixtures', (t) => {
   }
 })
 
-function fragment(htmlString) {
+function fragment(/** @type {string} */ htmlString) {
   const node = document.createDocumentFragment()
   const temporary = document.createElement('body')
 
@@ -170,6 +172,6 @@ function fragment(htmlString) {
   return node
 }
 
-function doc(htmlString) {
+function doc(/** @type {string} */ htmlString) {
   return new JSDOM(htmlString).window.document
 }

tsconfig.json

@@ -0,0 +1,15 @@
+{
+  "include": ["*.js", "lib/**/*.js", "test/**/*.js"],
+  "compilerOptions": {
+    "target": "ES2020",
+    "lib": ["ES2020", "DOM"],
+    "module": "ES2020",
+    "moduleResolution": "node",
+    "allowJs": true,
+    "checkJs": true,
+    "declaration": true,
+    "emitDeclarationOnly": true,
+    "allowSyntheticDefaultImports": true,
+    "skipLibCheck": true
+  }
+}