AngularJs custom sorting wont accept value returned from a function -

i'm calling api company uses returns array of objects, 1 of them looks like:

{ip = 127.0.0.1,  connected: 2015-01-01 00:00:00,  disconnected: 2015 01-01 01:00:00,  traffic:90000} 

i able create anugular app produces table ng-repeat sortable ip, connected, , disconnected. traffic var number of bytes transmitted during session subtracted dates number of bytes transmitted per second , able display on table table looks below. clicking headers sort table value , clicking again reverse , display appropriate arrow. results response http post:

js:

$scope.reverseorder = function(predicate) {     $scope.reverse = ($scope.predicate === predicate) ? !$scope.reverse : true ;     $scope.predicate = predicate; };     $scope.bytespersecond = function(startdate, enddate, traffic) {         var = moment(startdate);         var = moment(enddate);         var seconds = to.diff(from, 'seconds');         return traffic/seconds;     }; 

html:

<table class="...">         <thead>             <th>                 <a href="" ng-click="reverseorder('ip')">ip address</a>                 <i ng-class="{'icon-arrow-down' : reverse && predicate==='ip', 'icon-arrow-up' : !reverse && predicate==='ip'}"></i>             </th>             <th>                 <a href="" ng-click="reverseorder('connected')">time connected</a>                 <i ng-class="{'icon-arrow-down' : reverse && predicate==='connected', 'icon-arrow-up' : !reverse && predicate==='connected'}"></i>             </th>             <th>                 <a href="" ng-click="reverseorder('disconnected')">time disconnected</a>                 <i ng-class="{'icon-arrow-down' : reverse && predicate==='disconnected', 'icon-arrow-up' : !reverse && predicate==='disconnected'}"></i>             </th>             <th>                 <a href="" ng-click="reverseorder(bytespersecond)">bytes per second</a>                 <i ng-class="{'icon-arrow-down' : reverse && predicate===bytespersecond, 'icon-arrow-up' : !reverse && predicate===bytespersecond}"></i>             </th>         </tr>     </thead>     <tbody>         <tr ng-repeat="result in results | orderby:predicate:reverse">             <td style="text-align: left;">{{result.ip}}</td>             <td style="text-align: center;">{{result.connected}}</td>             <td style="text-align: center;">{{result.disconnected}}</td>             <td style="text-align: right;">{{bytespersecond(result.connected,result.disconnected,result.traffic)| number:0}}</td>         </tr>     </tbody> </table> 

the reverseorder function works ip , dates not work bytespersecond function. read in angular documentation orderby directive can used values functions i'm not sure why isn't working. displays , switches arrow next header , doesn't sort values @ all. how can table sort bytespersecond function created?

while there way make work using function order, lazy programmer doesn't want find out how it, i'd calculate bytes per second each item , store attribute.

angular.foreach($scope.results, function(value) {   value.bytespersecond = $scope.bytespersecond(value.connected, value.disconnected, value.traffic); }); 

and viola can share code other attributes =)