Convert DOMElementPool and specs to JS

src/dom-element-pool.coffee

@@ -1,55 +0,0 @@
-module.exports =
-class DOMElementPool
-  constructor: ->
-    @freeElementsByTagName = {}
-    @freedElements = new Set
-
-  clear: ->
-    @freedElements.clear()
-    for tagName, freeElements of @freeElementsByTagName
-      freeElements.length = 0
-    return
-
-  build: (tagName, factory, reset) ->
-    element = @freeElementsByTagName[tagName]?.pop()
-    element ?= factory()
-    reset(element)
-    @freedElements.delete(element)
-    element
-
-  buildElement: (tagName, className) ->
-    factory = -> document.createElement(tagName)
-    reset = (element) ->
-      delete element.dataset[dataId] for dataId of element.dataset
-      element.removeAttribute("style")
-      if className?
-        element.className = className
-      else
-        element.removeAttribute("class")
-    @build(tagName, factory, reset)
-
-  buildText: (textContent) ->
-    factory = -> document.createTextNode(textContent)
-    reset = (element) -> element.textContent = textContent
-    @build("#text", factory, reset)
-
-  freeElementAndDescendants: (element) ->
-    @free(element)
-    @freeDescendants(element)
-
-  freeDescendants: (element) ->
-    for descendant in element.childNodes by -1
-      @free(descendant)
-      @freeDescendants(descendant)
-    return
-
-  free: (element) ->
-    throw new Error("The element cannot be null or undefined.") unless element?
-    throw new Error("The element has already been freed!") if @freedElements.has(element)
-
-    tagName = element.nodeName.toLowerCase()
-    @freeElementsByTagName[tagName] ?= []
-    @freeElementsByTagName[tagName].push(element)
-    @freedElements.add(element)
-
-    element.remove()

src/dom-element-pool.js

@@ -0,0 +1,68 @@
+module.exports =
+class DOMElementPool {
+  constructor () {
+    this.freeElementsByTagName = {}
+    this.freedElements = new Set()
+  }
+
+  clear () {
+    this.freedElements.clear()
+    for (let tagName in this.freeElementsByTagName) {
+      const freeElements = this.freeElementsByTagName[tagName]
+      freeElements.length = 0
+    }
+  }
+
+  build (tagName, factory, reset) {
+    let element = this.freeElementsByTagName[tagName] ? this.freeElementsByTagName[tagName].pop() : null
+    if (!element) { element = factory() }
+    reset(element)
+    this.freedElements.delete(element)
+    return element
+  }
+
+  buildElement (tagName, className) {
+    const factory = () => document.createElement(tagName)
+    const reset = function (element) {
+      for (let dataId in element.dataset) { delete element.dataset[dataId] }
+      element.removeAttribute('style')
+      if (className != null) {
+        element.className = className
+      } else {
+        element.removeAttribute('class')
+      }
+    }
+    return this.build(tagName, factory, reset)
+  }
+
+  buildText (textContent) {
+    const factory = () => document.createTextNode(textContent)
+    const reset = element => { element.textContent = textContent }
+    return this.build('#text', factory, reset)
+  }
+
+  freeElementAndDescendants (element) {
+    this.free(element)
+    return this.freeDescendants(element)
+  }
+
+  freeDescendants (element) {
+    for (let i = element.childNodes.length - 1; i >= 0; i--) {
+      const descendant = element.childNodes[i]
+      this.free(descendant)
+      this.freeDescendants(descendant)
+    }
+  }
+
+  free (element) {
+    if (element == null) { throw new Error('The element cannot be null or undefined.') }
+    if (this.freedElements.has(element)) { throw new Error('The element has already been freed!') }
+
+    const tagName = element.nodeName.toLowerCase()
+    if (this.freeElementsByTagName[tagName] == null) { this.freeElementsByTagName[tagName] = [] }
+    this.freeElementsByTagName[tagName].push(element)
+    this.freedElements.add(element)
+
+    return element.remove()
+  }
+}