来看添加todo的html，绑定的model为newTodo，submit的方法是todoCtrl.js中的addTodo()，会添加一条todo，点击Enter，默认触发提交事件，就触发了addTodo()方法，添加了一条todo到todos中。
复制代码 代码如下:
<form ng-submit="addTodo()">
<input placeholder="What needs to be done?" ng-model="newTodo" autofocus>
</form>
再看展示todos的html
复制代码 代码如下:
<section ng-show="todos.length" ng-cloak>
<input type="checkbox" ng-model="allChecked" ng-click="markAll(allChecked)">
<label for="toggle-all">Mark all as complete</label>
<ul>
<li ng-repeat="todo in todos | filter:statusFilter track by $index" ng-class="{completed: todo.completed, editing: todo == editedTodo}">
<div>
<input type="checkbox" ng-model="todo.completed">
<label ng-dblclick="editTodo(todo)">{{todo.title}}</label>
<button ng-click="removeTodo(todo)"></button>
</div>
<form ng-submit="doneEditing(todo)">
<input ng-trim="false" ng-model="todo.title" todo-escape="revertEditing(todo)" ng-blur="doneEditing(todo)" todo-focus="todo == editedTodo">
</form>
</li>
</ul>
</section>
section使用ngShow方法根据todos的长度判断是否显示，加上ng-cloak属性是为了在刚开始时不要显示出AngularJS未处理的页面。可以去掉刷新试一试。
其中id为toggle-all的checkbox绑定到allChecked model上，点击触发markAll(allChecked)，将allChecked的值传入，标记所有的todos。