Add JSDoc based types

Author: wooorm

.gitignore

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

index.js

@@ -1,3 +1,13 @@
+/**
+ * @typedef {import('mdast').Heading} Heading
+ * @typedef {'atx'|'atx-closed'|'setext'} Style
+ */
+
+/**
+ * @param {Heading} node
+ * @param {Style} [relative]
+ * @returns {Style|null}
+ */
 export function headingStyle(node, relative) {
   var last = node.children[node.children.length - 1]
   var depth = node.depth
@@ -30,7 +40,13 @@ export function headingStyle(node, relative) {
   return consolidate(depth, relative)
 }
 
-// Get the probable style of an atx-heading, depending on preferred style.
+/**
+ * Get the probable style of an atx-heading, depending on preferred style.
+ *
+ * @param {number} depth
+ * @param {Style} relative
+ * @returns {Style|null}
+ */
 function consolidate(depth, relative) {
   return depth < 3
     ? 'atx'

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/mdast": "^3.0.0"
+  },
   "devDependencies": {
+    "@types/tape": "^4.0.0",
     "c8": "^7.0.0",
     "prettier": "^2.0.0",
     "remark": "^13.0.0",
     "remark-cli": "^9.0.0",
     "remark-preset-wooorm": "^8.0.0",
+    "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 \"*.d.ts\" && tsc && type-coverage",
     "format": "remark . -qfo && prettier . -w --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
   }
 }

test.js

@@ -4,10 +4,12 @@ import {headingStyle} from './index.js'
 
 test('headingStyle', function (t) {
   t.throws(function () {
+    // @ts-ignore runtime.
     headingStyle()
   }, 'should fail without node')
 
   t.equal(
+    // @ts-ignore runtime.
     headingStyle({
       type: 'heading',
       children: [{type: 'text', value: 'foo'}]

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
+  }
+}