angularjs – Angular orderBy数字排序为ng-repeat中的文本

[{"id":"42","firstname":"Sarah","lastname":"Dilby","age":"40","cars":"Yaris"},{"firstname":"Jason","lastname":"Diry","age":"5","id":"5"},{"id":"6","firstname":"Bilson","lastname":"Berby","age":"1","cars":"Tipo"}]

当我在ng-repeat中按顺序id或年龄时,它会将数字排序为文本.由于我无法在任何地方发现这是一个问题,我猜我的代码存在问题.我创建了这个小提琴：http://jsfiddle.net/vsbGH/1/抱歉模板,但jsfiddle不允许在html框中.无论如何,这是加载和排序数据的代码：

//user data
app.service('People',function() {
var People = {};
People.details = [{"id":"42","cars":"Tipo"}]
return People;
});

//list ctrl
controllers.listCtrl = function ($scope,People) {
 $scope.people = People.details;

 $scope.sortList = function(sortname) {
    $scope.sorter = sortname;
 }
}

这是模板的ng-repeat部分：

<tr ng-repeat="person in people | orderBy:sorter ">
        <td>{{person.id | number}}</td>
        <td>{{person.firstname}} </td>
        <td>{{person.lastname}} </td>
        <td>{{person.age | number}}</td>
        <td>{{person.cars}} </td>
 </tr>

非常感谢,如果你能帮助我理解为什么数字数据不是作为数字排序,以及为什么它作为文本排序.