AngularJS using $index with ng-repeat.

HTML

<div ng-app="myApp" ng-controller="MainCtrl">
    <ul>
        <li ng-repeat="page in pages | unique: 'customer.id'"   >
            <a ng-class="{ testClass: $index == pageNumber }" ng-click="setPageNumber($index)">{{ page.id }}</a>
        </li>
    </ul>
</div>

CSS

.testClass {
    background: black;
    color: white;
}

JavaScript

var app = angular.module('myApp', []);

app.controller('MainCtrl', function($scope) {
    $scope.pages = [
        { id:1, customer: { name: 'foo', id: 10 } },
  { id:2, customer: { name: 'bar', id: 20 } },
  { id:2, customer: { name: 'bar', id: 20 } },
  { id:2, customer: { name: 'bar', id: 20 } },
  { id:3, customer: { name: 'foo', id: 10 } },
  { id:4, customer: { name: 'bar', id: 20 } },
  { id:5, customer: { name: 'baz', id: 30 } },
    ];
    
    $scope.pageNumber = 0;
    $scope.setPageNumber = function(index) {
        $scope.pageNumber = index;
    }
});