Add ElementMorph.prototype.clear and ElementMorph.prototype.destroy.

packages/dom-helper/lib/main.js

@@ -114,6 +114,19 @@ function ElementMorph(element, dom, namespace) {
   this.isDirty = true;
 }
 
+// renderAndCleanup calls `clear` on all items in the morph map
+// just before calling `destroy` on the morph.
+//
+// As a future refactor this could be changed to set the property
+// back to its original/default value.
+ElementMorph.prototype.clear = function() { };
+
+ElementMorph.prototype.destroy = function() {
+  this.element = null;
+  this.dom = null;
+};
+
+
 /*
  * A class wrapping DOM functions to address environment compatibility,
  * namespaces, contextual elements for morph un-escaped content

packages/dom-helper/tests/dom-helper-test.js

@@ -87,7 +87,7 @@ test('#setAttributeNS', function(){
   // phantomjs omits the prefix, thus we can't find xlink:
   ok(el.innerHTML.indexOf('href="super-fun"') > 0);
   dom.setAttributeNS(node, xlinkNamespace, 'href', null);
-  
+
   ok(el.innerHTML.indexOf('href="null"') > 0);
 
 });
@@ -559,7 +559,7 @@ test('#setProperty with namespaced attributes', function() {
 
 test("#setProperty removes namespaced attr with undefined", function() {
   var node;
-  
+
   node = dom.createElement('svg');
   dom.setProperty(node, 'xlink:title', 'Great Title', xlinkNamespace);
   dom.setProperty(node, 'xlink:title', undefined, xlinkNamespace);

packages/dom-helper/tests/element-morph-test.js

@@ -0,0 +1,33 @@
+import DOMHelper from "../dom-helper";
+
+var dom;
+QUnit.module('DOM Helper: ElementMorph', {
+  beforeEach: function() {
+    dom = new DOMHelper();
+  },
+
+  afterEach: function() {
+    dom = null;
+  }
+});
+
+test('contains a clear method', function(){
+  expect(0);
+
+  var el = dom.createElement('div');
+  var node = dom.createElementMorph(el);
+
+  node.clear();
+});
+
+test('resets element and dom on destroy', function(){
+  expect(2);
+
+  var el = dom.createElement('div');
+  var node = dom.createElementMorph(el);
+
+  node.destroy();
+
+  equal(node.element, null, 'element was reset to null');
+  equal(node.dom, null, 'dom was reset to null');
+});