问没有用AngularJs中的过滤器正确评估负值(-1)？

EN

<div ng-controller="tagCtrl">
    <h5>filter object</h5>
    <li ng-repeat="cat in categoryToFilter()|filter: filterCategories" >
       <span class="cateNm">{{cat.catNm}}</span>
       <span ng-repeat="tag in tagCount|filter:{catId : cat.catId}">{{tag.tagNm}}|</span>
    </li>
</div>

var app = angular.module('app', []);
function tagCtrl($scope){
$scope.tagCount = [
    {catId:-1, catNm:"nagativeCategory", tagId:0, tagNm:"Z", count:50},
    {catId:1, catNm:"aCategory", tagId:1, tagNm:"A", count:50},
    {catId:2, catNm:"bCategory", tagId:2, tagNm:"B", count:30},
    {catId:3, catNm:"cCategory", tagId:3, tagNm:"C", count:20}
];

var indexedCategories = [];
$scope.categoryToFilter = function(){
    indexedCategories = [];
    return $scope.tagCount;
};

$scope.filterCategories = function(cat){
    var cateIsNew = indexedCategories.indexOf(cat.catId) == -1;
    if(cateIsNew){
        indexedCategories.push(cat.catId);
    }
    return cateIsNew;
};
}