Angular ngRepeat track by demo
HTML
<input type="text" ng-model='list'>
<!-- duplicate are forbidden so track by index -->
<ul>
<li ng-repeat="item in list.split(' ') track by $index">{{item}}</li>
</ul>
JavaScript
var app = angular.module('app', [$scope]);
$scope.test = 'ddd';
angular.bootstrap(document.body, ['app'])