knockoutjs_require: Cancel edits using Escape key

Ref #789

Design pattern and some code taken from examples/requirejs.

examples/knockoutjs_require/index.html

@@ -22,7 +22,7 @@
 							<label data-bind="text: title, event: { dblclick: $root.editItem }"></label>
 							<button class="destroy" data-bind="click: $root.remove"></button>
 						</div>
-						<input class="edit" data-bind="value: title, valueUpdate: 'afterkeydown', enterKey: $root.stopEditing, selectAndFocus: editing, event: { blur: $root.stopEditing }">
+						<input class="edit" data-bind="value: title, valueUpdate: 'afterkeydown', enterKey: $root.stopEditing, escapeKey: $root.cancelEditing, selectAndFocus: editing, event: { blur: $root.stopEditing }">
 					</li>
 				</ul>
 			</section>

examples/knockoutjs_require/js/config/global.js

@@ -4,5 +4,6 @@
 
 define({
 	ENTER_KEY: 13,
+	ESCAPE_KEY: 27,
 	localStorageItem: 'todos-knockout-require'
 });

examples/knockoutjs_require/js/extends/handlers.js

@@ -6,15 +6,14 @@ define([
 ], function (ko, g) {
 	'use strict';
 
-	// a custom binding to handle the enter key (could go in a separate library)
-	ko.bindingHandlers.enterKey = {
+	function keyupBindingFactory(keyCode) {
+		return {
 			init: function (element, valueAccessor, allBindingsAccessor, data, bindingContext) {
-			var wrappedHandler;
-			var newValueAccessor;
+				var wrappedHandler, newValueAccessor;
 
 				// wrap the handler with a check for the enter key
 				wrappedHandler = function (data, event) {
-				if (event.keyCode === g.ENTER_KEY) {
+					if (event.keyCode === keyCode) {
 						valueAccessor().call(this, data, event);
 					}
 				};
@@ -30,6 +29,10 @@ define([
 				ko.bindingHandlers.event.init(element, newValueAccessor, allBindingsAccessor, data, bindingContext);
 			}
 		};
+	}
+
+	ko.bindingHandlers.enterKey = keyupBindingFactory(g.ENTER_KEY);
+	ko.bindingHandlers.escapeKey = keyupBindingFactory(g.ESCAPE_KEY);
 
 	// wrapper to hasfocus that also selects text and applies focus async
 	ko.bindingHandlers.selectAndFocus = {

examples/knockoutjs_require/js/viewmodels/todo.js

@@ -44,6 +44,7 @@ define([
 		// edit an item
 		self.editItem = function (item) {
 			item.editing(true);
+			item.previousTitle = item.title();
 		};
 
 		// stop editing an item.  Remove the item, if it is now empty
@@ -65,6 +66,12 @@ define([
 			}
 		};
 
+		// cancel editing an item and revert to the previous content
+		self.cancelEditing = function (item) {
+			item.editing(false);
+			item.title(item.previousTitle);
+		};
+
 		// count of all completed todos
 		self.completedCount = ko.computed(function () {
 			return ko.utils.arrayFilter(self.todos(), function (todo) {