angularjs filter not filter multipe filter值

<div ng-app="myApp" ng-controller="myCtrl">
  <input type="text" ng-model="searchText" placeholder="Search...">
  <ul>
    <li ng-repeat="item in items | filter:searchText | filter:filterByCategory">{{item.name}}</li>
  </ul>
</div>

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

  app.controller('myCtrl', function($scope) {
    $scope.items = [
      {name: 'Apple', category: 'Fruit'},
      {name: 'Banana', category: 'Fruit'},
      {name: 'Carrot', category: 'Vegetable'},
      {name: 'Tomato', category: 'Vegetable'}
    ];

    $scope.filterByCategory = function(item) {
      if (!$scope.categoryFilter) {
        return true;
      }
      return item.category === $scope.categoryFilter;
    };
  });
</script>