AngularJS - Summing filtered rows in table - angularjs

Question

Based in this example I need to sum the ages of the filtered users. It means, if I have three names filtered, the filter in the controller must to sum only these the ages.
html
<div data-ng-app="app" data-ng-controller="controller">
<input type="text" data-ng-model="parameter" placeholder="search">
<p/>
<table border="1">
<thead>
<tr>
<th>#</th>
<th>Name</th>
<th>Age</th>
</tr>
<thead>
<tbody>
<tr data-ng-repeat="user in users | filter: parameter">
<td>{{$index+1}}</td>
<td>{{user.name}}</td>
<td>{{user.age}}</td>
</tr>
</tbody>
<tfoot>
<tr>
<td colspan="2">Total ages</td>
<td>{{users | sumByKey: 'age'}}</td>
</tr>
</tfoot>
</table>
</div>
angularjs
var app = angular.module("app", []);
app.filter('sumByKey', function() {
return function(data, key) {
if (typeof(data) === 'undefined' || typeof(key) === 'undefined') {
return 0;
}
var sum = 0;
for (var i = data.length - 1; i >= 0; i--) {
sum += parseInt(data[i][key]);
}
return sum;
};
});
Any idea?

Answer 1

You could store the filtered data in a filteredList and pass it for the calculation,
<tbody>
<tr data-ng-repeat="user in (filteredList = (users | filter: parameter))">
<td>{{$index+1}}</td>
<td>{{user.name}}</td>
<td>{{user.age}}</td>
</tr>
</tbody>
<tfoot>
<tr>
<td colspan="2">Total ages</td>
<td>{{filteredList | sumByKey: 'age' }}</td>
</tr>
</tfoot>
DEMO