get count of items with some property in an array

Question

I have an array of objects as follow.

$scope.students = [{'isSelected': true},     {'isSelected': true},     {'isSelected': false},     {'isSelected': true},     {'isSelected': true}, ] 

How can i get the count items that have isSelected property set to true ?

UPDATE:

The problem is $scope.students is fetched from a REST api and simply looping over the $scope.students variable does not work as the variable is undefined until the request is completed, and so the loop code errors out saying $scope.students is not defined.

I tried using $watch but in that case i have to define the loop under the watch directive and it only works one time when $scope.students is defined, after that the loop does not work as $scope.students itself is not changing.

Answer 1

There is another way to do this: the AngularJS filters. You can write this:

var selectedCount = $filter('filter')($scope.students, { isSelected: true }).length;