angularjs filter array of objects with object in value

Question

if i have simple object like this:

$scope.results = {
  year:2021,
  subjects:[
    {title:'English',grade:'A'},
    {title:'Maths',grade:'A'},
    {title:'Science',grade:'B'},
    {title:'Geography',grade:'C'}
  ]
};

IT IS NO PROBLEM to get value using filter, like here

 $scope.gradeC = $filter('filter')($scope.results.subjects, {grade: 'C'})[0];

or count it :

 $scope.gradeA = $filter('filter')($scope.results.subjects, {grade: 'A'}).length;

BUT, if i have something like this:

$scope.results = {
  year:2021,
  subjects:[
    {title:'English',grade:''},
    {title:'Maths',grade:''},
    {title:'Science',grade:''},
    {title:'Geography',grade:'{
                 _someDate : 'Nov 19, 2024'
             }'}
  ]
};

how could i to count how much values in grade with empty string i have and how much with some Object as value?

Answer 1

A filter is useful in the view. But in the JS code, you have all the power of standard JS functions with you:

var countWithEmptyGrade = $scope.results.subjects.filter(function(subject) {
    return subject.grade === '';
}).length;