Add JSDoc based types

.gitignore

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

index.js

@@ -1,10 +1,34 @@
 import {arrayIterate} from 'array-iterate'
 
-// Turn `callback` into a child-modifier accepting a parent.  See
-// `array-iterate` for more info.
+/**
+ * @typedef {import('unist').Parent} Parent
+ * @typedef {import('unist').Node} Node
+ *
+ * @callback Modifier
+ * @param {Node} node
+ * @param {number} index
+ * @param {Parent} parent
+ * @returns {number|void}
+ *
+ * @callback Modify
+ * @param {Parent} node
+ * @returns {void}
+ */
+
+/**
+ * Turn `callback` into a child-modifier accepting a parent.
+ * See `array-iterate` for more info.
+ *
+ * @param {Modifier} callback
+ * @returns {Modify}
+ */
 export function modifyChildren(callback) {
   return iterator
 
+  /**
+   * @param {Parent} parent
+   * @returns {void}
+   */
   function iterator(parent) {
     if (!parent || !parent.children) {
       throw new Error('Missing children in `parent` for `modifier`')
@@ -13,8 +37,14 @@ export function modifyChildren(callback) {
     arrayIterate(parent.children, iteratee, parent)
   }
 
-  // Pass the context as the third argument to `callback`.
-  function iteratee(value, index) {
-    return callback(value, index, this)
+  /**
+   * Pass the context as the third argument to `callback`.
+   *
+   * @this {Parent}
+   * @param {Node} node
+   * @param {number} index
+   */
+  function iteratee(node, index) {
+    return callback(node, index, this)
   }
 }

package.json

@@ -27,30 +27,36 @@
   "sideEffects": false,
   "type": "module",
   "main": "index.js",
-  "types": "types/index.d.ts",
+  "types": "index.d.ts",
   "files": [
-    "index.js",
-    "types/index.d.ts"
+    "index.d.ts",
+    "index.js"
   ],
   "dependencies": {
+    "@types/unist": "^2.0.0",
     "array-iterate": "^2.0.0"
   },
   "devDependencies": {
+    "@types/tape": "^4.0.0",
     "c8": "^7.0.0",
     "dtslint": "^4.0.0",
     "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",
     "unified": "^9.0.0",
     "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-types": "dtslint types",
-    "test": "npm run format && npm run test-coverage && npm run test-types"
+    "test": "npm run build && npm run format && npm run test-coverage"
   },
   "prettier": {
     "tabWidth": 2,
@@ -71,5 +77,10 @@
     "plugins": [
       "preset-wooorm"
     ]
+  },
+  "typeCoverage": {
+    "atLeast": 100,
+    "detail": true,
+    "strict": true
   }
 }

test.js

@@ -1,11 +1,12 @@
 import test from 'tape'
 import {modifyChildren} from './index.js'
 
-var noop = Function.prototype
+function noop() {}
 
 test('modifyChildren()', function (t) {
   t.throws(
     function () {
+      // @ts-ignore runtime.
       modifyChildren(noop)()
     },
     /Missing children in `parent`/,
@@ -14,22 +15,26 @@ test('modifyChildren()', function (t) {
 
   t.throws(
     function () {
+      // @ts-ignore runtime.
       modifyChildren(noop)({})
     },
     /Missing children in `parent`/,
     'should throw without parent'
   )
 
   t.test('should invoke `fn` for each child in `parent`', function (st) {
-    var values = [0, 1, 2, 3]
-    var context = {}
+    var children = [
+      {type: 'x', value: 0},
+      {type: 'x', value: 1},
+      {type: 'x', value: 2},
+      {type: 'x', value: 3}
+    ]
+    var context = {type: 'y', children}
     var n = -1
 
-    context.children = values
-
     modifyChildren(function (child, index, parent) {
       n++
-      st.strictEqual(child, values[n])
+      st.strictEqual(child, children[n])
       st.strictEqual(index, n)
       st.strictEqual(parent, context)
     })(context)
@@ -38,63 +43,109 @@ test('modifyChildren()', function (t) {
   })
 
   t.test('should work when new children are added', function (st) {
-    var values = [0, 1, 2, 3, 4, 5, 6]
+    var children = [
+      {type: 'x', value: 0},
+      {type: 'x', value: 1},
+      {type: 'x', value: 2},
+      {type: 'x', value: 3},
+      {type: 'x', value: 4},
+      {type: 'x', value: 5},
+      {type: 'x', value: 6}
+    ]
     var n = -1
 
     modifyChildren(function (child, index, parent) {
       n++
 
       if (index < 3) {
-        parent.children.push(parent.children.length)
+        parent.children.push({type: 'x', value: parent.children.length})
       }
 
-      st.strictEqual(child, values[n])
-      st.strictEqual(index, values[n])
-    })({children: [0, 1, 2, 3]})
+      st.deepEqual(child, children[n])
+      st.deepEqual(index, n)
+    })({
+      type: 'y',
+      children: [
+        {type: 'x', value: 0},
+        {type: 'x', value: 1},
+        {type: 'x', value: 2},
+        {type: 'x', value: 3}
+      ]
+    })
 
     st.end()
   })
 
   t.test('should skip forwards', function (st) {
-    var values = [0, 1, 2, 3]
+    var children = [
+      {type: 'x', value: 0},
+      {type: 'x', value: 1},
+      {type: 'x', value: 2},
+      {type: 'x', value: 3}
+    ]
     var n = -1
-    var context = {}
-
-    context.children = [0, 1, 3]
+    var context = {
+      type: 'y',
+      children: [
+        {type: 'x', value: 0},
+        {type: 'x', value: 1},
+        {type: 'x', value: 3}
+      ]
+    }
 
     modifyChildren(function (child, index, parent) {
-      st.strictEqual(child, values[++n])
+      st.deepEqual(child, children[++n])
 
-      if (child === 1) {
-        parent.children.splice(index + 1, 0, 2)
+      if (child.value === 1) {
+        parent.children.splice(index + 1, 0, {type: 'x', value: 2})
         return index + 1
       }
     })(context)
 
-    st.deepEqual(context.children, values)
+    st.deepEqual(context.children, children)
 
     st.end()
   })
 
   t.test('should skip backwards', function (st) {
-    var invocations = [0, 1, -1, 0, 1, 2, 3]
+    var calls = [
+      {type: 'x', value: 0},
+      {type: 'x', value: 1},
+      {type: 'x', value: -1},
+      {type: 'x', value: 0},
+      {type: 'x', value: 1},
+      {type: 'x', value: 2},
+      {type: 'x', value: 3}
+    ]
     var n = -1
-    var context = {}
-    var inserted
-
-    context.children = [0, 1, 2, 3]
-
-    modifyChildren(function (child, index, parent) {
-      st.strictEqual(child, invocations[++n])
-
-      if (!inserted && child === 1) {
+    var context = {
+      type: 'y',
+      children: [
+        {type: 'x', value: 0},
+        {type: 'x', value: 1},
+        {type: 'x', value: 2},
+        {type: 'x', value: 3}
+      ]
+    }
+    var inserted = false
+
+    modifyChildren(function (child, _, parent) {
+      st.deepEqual(child, calls[++n])
+
+      if (!inserted && child.value === 1) {
         inserted = true
-        parent.children.unshift(-1)
+        parent.children.unshift({type: 'x', value: -1})
         return -1
       }
     })(context)
 
-    st.deepEqual(context.children, [-1, 0, 1, 2, 3])
+    st.deepEqual(context.children, [
+      {type: 'x', value: -1},
+      {type: 'x', value: 0},
+      {type: 'x', value: 1},
+      {type: 'x', value: 2},
+      {type: 'x', value: 3}
+    ])
 
     st.end()
   })

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
+  }
+}