Javascript &引用；“ng类”；在每个单击的项目上

我需要在所选的

上添加一个类，就像我在演示中显示的那样，但如果我单击另一个

，我不希望将其删除

请帮忙

<div ng-app="myApp">
    <ul ng-controller="myCtrl">
        <li ng-repeat="item in model.items" class="commonClass" ng-class="{'on': model.selected==item}" ng-click="model.selected=item">{{ item.name }}</li>
    </ul>
</div>

只需像这样添加

<div ng-app="myApp">
    <ul ng-controller="myCtrl">
        <li ng-repeat="item in model.items" class="commonClass" ng-class="{'on': selected==$index}" ng-click="selected=$index">{{ item.name }}</li>
    </ul>
</div>

{{{item.name}

<div ng-app="myApp">
    <ul ng-controller="myCtrl">
        <li ng-repeat="item in model.items" class="commonClass" ng-class="{'on': selected==$index}" ng-click="selected=$index">{{ item.name }}</li>
    </ul>
</div>