javascript - Angular，同步两个选择元素

Question

我正在努力理解绑定(bind)和选择元素。我想要同步两个选择元素。看起来 ng-value="$index"应该是正确的方法，但它不起作用。

这些同步:

<select  ng-model="myVar1"><option value="{{n}}" ng-repeat="(n, o) in ['donny', 'felix', 'bob'] track by $index" >{{o}}</option></select>

{{o}}

但这些没有:

<select  ng-model="myVar2"><option ng-value="$index" ng-repeat="o in ['donny', 'felix', 'bob'] track by $index" >{{o}}</option></select> <select  ng-model="myVar2"> <option ng-value="$index" ng-repeat="o in ['donny', 'felix', 'bob'] track by $index" >{{o}}</option>   </select>

JSBIN: http://jsbin.com/dirugikice/1/edit?html,js,output

我错过了什么？

Answer 1

将 $index 括在括号中，例如 {$index}

<select  ng-model="myVar2"><option ng-value="{$index}" ng-repeat="o in ['donny', 'felix', 'bob'] track by $index" >{{o}}</option></select> <select  ng-model="myVar2"> <option ng-value="{$index}" ng-repeat="o in ['donny', 'felix', 'bob'] track by $index" >{{o}}</option>   </select>

http://jsbin.com/pubapigibi/1/edit