Add JSDoc based types

Author: wooorm

Diff for: .gitignore

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

Diff for: index.js

@@ -1,29 +1,42 @@
-// Stringify one nlcst node or list of nodes.
+/**
+ * @typedef {import('unist').Node} Node
+ */
+
+/**
+ * Stringify one nlcst node or list of nodes.
+ *
+ * @param {unknown} node
+ * @param {string} [separator='']
+ * @returns {string}
+ */
 export function toString(node, separator = '') {
-  var values
-  var length
+  var index = -1
+  /** @type {Array.<Node>} */
   var children
+  /** @type {Array.<string>} */
+  var values
 
-  if (!node || (!('length' in node) && !node.type)) {
+  // @ts-ignore Looks like an object.
+  if (!node || (!Array.isArray(node) && !node.type)) {
     throw new Error('Expected node, not `' + node + '`')
   }
 
-  if (typeof node.value === 'string') {
-    return node.value
-  }
+  // @ts-ignore Looks like a literal.
+  if (typeof node.value === 'string') return node.value
 
+  // @ts-ignore Looks like a list of nodes or parent.
   children = 'length' in node ? node : node.children
-  length = children.length
 
   // Shortcut: This is pretty common, and a small performance win.
-  if (length === 1 && 'value' in children[0]) {
+  if (children.length === 1 && 'value' in children[0]) {
+    // @ts-ignore Looks like a literal.
     return children[0].value
   }
 
   values = []
 
-  while (length--) {
-    values[length] = toString(children[length], separator)
+  while (++index < children.length) {
+    values[index] = toString(children[index], separator)
   }
 
   return values.join(separator)

Diff for: 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/unist": "^2.0.0"
+  },
   "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": "^3.0.0",
     "tape": "^5.0.0",
+    "type-coverage": "^2.0.0",
+    "typescript": "^4.0.0",
     "unist-builder": "^3.0.0",
     "xo": "^0.38.0"
   },
   "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
   }
 }

Diff for: 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
+  }
+}