在angular中使用ng-repeat时数组中有重复元素，要用item in items track by $index

在angular中使用ng-repeat时数组中有重复元素，要用item in items track by $index，不然会报错

<div class="" ng-init="names=[1,2,3,4,5,5]">
    <p>循环对象:</p>
    <ul>
    <li ng-repeat="x in names track by $index">
    {{ x }}</li>
    </ul>

  </div>

  <script type="text/javascript">
  var app=angular.module('myApp',[]);

  </script>