Backbone apps - simplify `clearCompleted` logic

architecture-examples/backbone/js/views/app.js

@@ -111,10 +111,7 @@ $(function( $ ) {
 
 		// Clear all completed todo items, destroying their models.
 		clearCompleted: function() {
-			_.each( app.Todos.completed(), function( todo ) {
-				todo.destroy();
-			});
-
+			_.invoke(app.Todos.completed(), 'destroy');
 			return false;
 		},
 

dependency-examples/backbone_require/js/views/app.js

@@ -112,10 +112,7 @@ define([
 
 		// Clear all completed todo items, destroying their models.
 		clearCompleted: function() {
-			_.each( Todos.completed(), function( todo ) {
-				todo.destroy();
-			});
-
+			_.invoke(Todos.completed(), 'destroy');
 			return false;
 		},