title: Angular - compare many old and new values
body: <p>Using Angular, is it possible to compare an old and new value when it is changed (programmatically, or otherwise)?</p>
  
  <p>I guess what I'm after is functionality similar to ng-change that can be applied to any element and is triggered whenever the value in the expression is updated.</p>
  
  <p>Of course, I could use $scope.$watch on the entire data model, find the individual changed values (and injecting a 'changeDirection' property) but this feels excessive.</p>
  
  <p>Edit: Consider a data model of an array of 500 objects, each with 5 properties, 2 of which are integers that I need to know if they have increased/decreased.</p>