AngularJS $scope and array - bug or feature?

Question

JavaScript

I'm almost a complete zero in JS, but I got someone else's code and I have to poke around. Faced strange behavior (in my opinion this is a bug).
In the controller I do
$scope.item = $scope.arrayFirst[i]
, then in the code -
$scope.someArray.push($scope.item)
And so 20 iterations. So, in some conditions that I can’t trace, when pushing one of the items in the array, o_0 disappears, that is, its length becomes one less. So far I have solved the problem like this:
$scope.item = angular.copy($scope.arrayFirst[i])
- it seems to work fine.
What could it be? Can angular somehow filter this array without my knowledge?

Answer 1

filter this array without my knowledge?

no, but the array can be modified from another part of the system, for example if it is passed into a directive.