Refactor to use class

Author: wooorm

index.js

@@ -1,80 +1,60 @@
 import {visit} from 'unist-util-visit'
 
-Index.prototype.get = get
-Index.prototype.add = add
-Index.prototype.remove = remove
-
-export function Index(tree, filter, prop) {
-  var self
-
-  if (!(this instanceof Index)) {
-    return new Index(tree, filter, prop)
-  }
-
-  if (prop === null || prop === undefined) {
-    if (filter === null || filter === undefined) {
-      prop = tree
-      tree = null
-    } else {
-      prop = filter
+export class Index {
+  constructor(tree, filter, prop) {
+    var pluck = (node) => node[prop]
+
+    if (prop === null || prop === undefined) {
+      if (filter === null || filter === undefined) {
+        prop = tree
+        tree = null
+      } else {
+        prop = filter
+      }
+
+      filter = trueConst
     }
 
-    filter = trueConst
-  }
-
-  self = this
-
-  this.index = new Map()
-  this.keyfn = typeof prop === 'string' ? pluck : prop
-
-  if (tree) {
-    visit(tree, filter, add)
-  }
-
-  return this
+    this.index = new Map()
+    this.keyfn = typeof prop === 'string' ? pluck : prop
 
-  function pluck(node) {
-    return node[prop]
+    if (tree) {
+      visit(tree, filter, (node) => this.add(node))
+    }
   }
 
-  function add(node) {
-    self.add(node)
+  get(key) {
+    return this.index.get(key) || []
   }
-}
 
-function get(key) {
-  return this.index.get(key) || []
-}
+  add(node) {
+    var key = this.keyfn(node)
+    var nodes
 
-function add(node) {
-  var self = this
-  var key = self.keyfn(node)
-  var nodes
+    if (!this.index.has(key)) {
+      this.index.set(key, [])
+    }
 
-  if (!self.index.has(key)) {
-    self.index.set(key, [])
-  }
+    nodes = this.index.get(key)
 
-  nodes = self.index.get(key)
+    if (!nodes.includes(node)) {
+      nodes.push(node)
+    }
 
-  if (nodes.indexOf(node) === -1) {
-    nodes.push(node)
+    return this
   }
 
-  return self
-}
+  remove(node) {
+    var key = this.keyfn(node)
+    var nodes = this.index.get(key)
+    var pos = nodes ? nodes.indexOf(node) : -1
 
-function remove(node) {
-  var self = this
-  var key = self.keyfn(node)
-  var nodes = self.index.get(key)
-  var pos = nodes ? nodes.indexOf(node) : -1
+    if (pos !== -1) {
+      nodes.splice(pos, 1)
+    }
 
-  if (pos !== -1) {
-    nodes.splice(pos, 1)
+    return this
   }
-
-  return self
 }
 
 function trueConst() {

package.json

@@ -68,8 +68,6 @@
   "xo": {
     "prettier": true,
     "rules": {
-      "unicorn/no-this-assignment": "off",
-      "unicorn/prefer-includes": "off",
       "no-var": "off",
       "prefer-arrow-callback": "off"
     }

test.js

@@ -3,22 +3,11 @@ import {u} from 'unist-builder'
 import {select} from 'unist-util-select'
 import {Index} from './index.js'
 
-var index = Index
-
 test('Index', function (t) {
   var node = {type: 'a', id: 1}
   var alt = {type: 'b', id: 1}
   var tree = {type: 'root', children: [node, alt]}
-  var instance = index('id')
-  instance.add(node)
-
-  t.deepEqual(
-    [instance instanceof Index, instance.get(1)],
-    [true, [node]],
-    'index(prop)'
-  )
-
-  instance = new Index('id')
+  var instance = new Index('id')
   instance.add(node)
 
   t.deepEqual(
@@ -27,15 +16,6 @@ test('Index', function (t) {
     'new Index(prop)'
   )
 
-  instance = index(keyFn)
-  instance.add(node)
-
-  t.deepEqual(
-    [instance instanceof Index, instance.get(1)],
-    [true, [node]],
-    'index(keyFn)'
-  )
-
   instance = new Index(keyFn)
   instance.add(node)
 
@@ -45,14 +25,6 @@ test('Index', function (t) {
     'new Index(keyFn)'
   )
 
-  instance = index(tree, 'id')
-
-  t.deepEqual(
-    [instance instanceof Index, instance.get(1)],
-    [true, [node, alt]],
-    'index(tree, prop)'
-  )
-
   instance = new Index(tree, 'id')
 
   t.deepEqual(
@@ -61,14 +33,6 @@ test('Index', function (t) {
     'new Index(tree, prop)'
   )
 
-  instance = index(tree, filter, 'id')
-
-  t.deepEqual(
-    [instance instanceof Index, instance.get(1)],
-    [true, [node]],
-    'index(tree, filter, prop)'
-  )
-
   instance = new Index(tree, filter, 'id')
 
   t.deepEqual(