Add types

package.json

@@ -15,28 +15,35 @@
   "author": "azu <[email protected]>",
   "contributors": [
     "azu <[email protected]>",
-    "Titus Wormer <[email protected]> (https://wooorm.com)"
+    "Titus Wormer <[email protected]> (https://wooorm.com)",
+    "Christian Murphy <[email protected]>"
   ],
   "files": [
-    "index.js"
+    "index.js",
+    "types/index.d.ts"
   ],
+  "types": "types/index.d.ts",
   "dependencies": {
+    "@types/mdast": "^3.0.3",
     "object-assign": "^4.0.1"
   },
   "devDependencies": {
+    "dtslint": "^0.9.9",
     "nyc": "^14.0.0",
     "prettier": "^1.0.0",
     "remark-cli": "^6.0.0",
     "remark-preset-wooorm": "^5.0.0",
     "tape": "^4.10.1",
     "unist-builder": "^1.0.3",
+    "unist-util-is": "^4.0.0",
     "xo": "^0.24.0"
   },
   "scripts": {
     "format": "remark . -qfo && prettier --write \"**/*.js\" && xo --fix",
     "test-api": "node test",
     "test-coverage": "nyc --reporter lcov tape test.js",
-    "test": "npm run format && npm run test-coverage"
+    "test-types": "dtslint types",
+    "test": "npm run format && npm run test-coverage && npm run test-types"
   },
   "nyc": {
     "check-coverage": true,

types/index.d.ts

@@ -0,0 +1,19 @@
+// TypeScript Version: 3.5
+
+import {Node} from 'unist'
+
+declare namespace unistUtilMap {
+  type MapFunction = (node: Node, index: number | null, parent: Node | null) => Node
+}
+
+/**
+ * unist utility to create a new tree by mapping all nodes with the given function.
+ *
+ * @param tree Tree to map
+ * @param callback Function that returns a new node
+ * @returns Node to be used in the new tree.
+ *   Its children are not used: if the original node has children, those are mapped.
+ */
+declare function unistUtilMap(tree: Node, callback: unistUtilMap.MapFunction): Node
+
+export = unistUtilMap

types/tsconfig.json

@@ -0,0 +1,10 @@
+{
+  "compilerOptions": {
+    "lib": ["es2015"],
+    "strict": true,
+    "baseUrl": ".",
+    "paths": {
+      "unist-util-map": ["index.d.ts"]
+    }
+  }
+}

types/tslint.json

@@ -0,0 +1,7 @@
+{
+  "extends": "dtslint/dtslint.json",
+  "rules": {
+    "whitespace": false,
+    "semicolon": false
+  }
+}

types/unist-util-map-tests.ts

@@ -0,0 +1,37 @@
+import * as map from 'unist-util-map'
+import * as is from 'unist-util-is'
+import {Node} from 'unist'
+import {Heading, Paragraph} from 'mdast'
+
+// $ExpectType Node
+map({type: 'root'}, (node: Node) => ({type: node.type + 'test'}))
+// $ExpectType Node
+map({type: 'root'}, (node: Node, index: number | null) => ({
+  type: node.type + 'test'
+}))
+// $ExpectType Node
+map(
+  {type: 'root'},
+  (node: Node, index: number | null, parent: Node | null) => ({
+    type: node.type + 'test'
+  })
+)
+// $ExpectType Node
+map({type: 'root'}, (node: Node) => {
+  if (is<Heading>(node, 'heading')) {
+    const depth = node.depth < 5 ? node.depth + 1 : 6
+    return {
+      ...node,
+      depth
+    }
+  }
+
+  if (is<Paragraph>(node, 'paragraph')) {
+    return {
+      type: 'strong',
+      children: node.children
+    }
+  }
+
+  return node
+})