Add JSDoc based types

Author: wooorm

.gitignore

@@ -1,4 +1,5 @@
 .DS_Store
+*.d.ts
 *.log
 coverage/
 node_modules/

index.js

@@ -1,18 +1,43 @@
+/**
+ * @typedef {import('xast').Root} Root
+ * @typedef {import('xast').Element} Element
+ * @typedef {import('xast').RootChildMap} RootChildMap
+ * @typedef {RootChildMap[keyof RootChildMap]} Child
+ * @typedef {Root|Child} Node
+ * @typedef {Root|Element} Parent
+ */
+
+/**
+ * @param {Node} node
+ * @returns {string}
+ */
 export function toString(node) {
   // A root or an element
+  // @ts-ignore Looks like a parent.
   if ('children' in node) return all(node)
+  // @ts-ignore Looks like a literal.
   return 'value' in node ? node.value : ''
 }
 
+/**
+ * @param {Node} node
+ * @returns {string}
+ */
 function one(node) {
   if (node.type === 'text') return node.value
   // Ignore things like comments, instruction, cdata.
+  // @ts-ignore Looks like a parent.
   return node.children ? all(node) : ''
 }
 
+/**
+ * @param {Parent} node
+ * @returns {string}
+ */
 function all(node) {
   var children = node.children
   var index = -1
+  /** @type {Array.<string>} */
   var result = []
 
   while (++index < children.length) {

package.json

@@ -27,23 +27,34 @@
   "sideEffects": false,
   "type": "module",
   "main": "index.js",
+  "types": "index.d.ts",
   "files": [
+    "index.d.ts",
     "index.js"
   ],
+  "dependencies": {
+    "@types/xast": "^1.0.0"
+  },
   "devDependencies": {
+    "@types/tape": "^4.0.0",
     "c8": "^7.0.0",
     "prettier": "^2.0.0",
     "remark-cli": "^9.0.0",
     "remark-preset-wooorm": "^8.0.0",
+    "rimraf": "^3.0.2",
     "tape": "^5.0.0",
+    "type-coverage": "^2.17.5",
+    "typescript": "^4.2.4",
     "unist-builder": "^3.0.0",
     "xo": "^0.39.0"
   },
   "scripts": {
+    "prepack": "npm run build && npm run format",
+    "build": "rimraf \"*.d.ts\" && tsc && type-coverage",
     "format": "remark . -qfo && prettier . --write --loglevel warn && xo --fix",
     "test-api": "node test.js",
     "test-coverage": "c8 --check-coverage --branches 100 --functions 100 --lines 100 --statements 100 --reporter lcov node test.js",
-    "test": "npm run format && npm run test-coverage"
+    "test": "npm run build && npm run format && npm run test-coverage"
   },
   "prettier": {
     "tabWidth": 2,
@@ -64,5 +75,10 @@
     "plugins": [
       "preset-wooorm"
     ]
+  },
+  "typeCoverage": {
+    "atLeast": 100,
+    "detail": true,
+    "strict": true
   }
 }

tsconfig.json

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