Add JSDoc based types

Author: wooorm

.gitignore

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

index.js

@@ -1,6 +1,18 @@
+/**
+ * @typedef {import('unist').Node} UnistNode
+ * @typedef {import('hast').Element} HastElement
+ * @typedef {import('unist-util-visit').Visitor<HastElement>} VisitElement
+ */
+
 import {headingRank} from 'hast-util-heading-rank'
 import {visit} from 'unist-util-visit'
 
+/**
+ * @template {UnistNode} T
+ * @param {T} tree
+ * @param {number} shift
+ * @returns {T}
+ */
 export function shiftHeading(tree, shift) {
   if (
     typeof shift !== 'number' ||
@@ -15,6 +27,7 @@ export function shiftHeading(tree, shift) {
 
   return tree
 
+  /** @type {VisitElement} */
   function visitor(node) {
     var rank = headingRank(node)
 

package.json

@@ -30,27 +30,37 @@
   "sideEffects": false,
   "type": "module",
   "main": "index.js",
+  "types": "index.d.ts",
   "files": [
+    "index.d.ts",
     "index.js"
   ],
   "dependencies": {
+    "@types/hast": "^2.0.0",
+    "@types/unist": "^2.0.0",
     "hast-util-heading-rank": "^2.0.0",
     "unist-util-visit": "^3.0.0"
   },
   "devDependencies": {
+    "@types/tape": "^4.0.0",
     "c8": "^7.0.0",
     "hastscript": "^7.0.0",
     "prettier": "^2.0.0",
     "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,
@@ -71,5 +81,10 @@
     "plugins": [
       "preset-wooorm"
     ]
+  },
+  "typeCoverage": {
+    "atLeast": 100,
+    "detail": true,
+    "strict": true
   }
 }

test.js

@@ -5,6 +5,7 @@ import {shiftHeading} from './index.js'
 test('shiftHeading', function (t) {
   t.throws(
     function () {
+      // @ts-ignore runtime.
       shiftHeading(h(''))
     },
     /^Error: Expected a non-null finite integer, not `undefined`$/,

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
+  }
+}