AngularJS $watch vs $watchCollection: which is better for performance?

Question

For watching an object scope variable, is $scope.$watch with objectEquality set to true OR $scope.$watchCollection better?

For

Answer 1

$watchCollection is optimized for vector arrays [] where elements can be push

and $watch is good for associative arrays objects {}

$watchCollection will not watch for depth changes, is like watch with objectEquality set to false.

If you already know to structure of the depth you can optimize like this:

  // ctrl watch ?
  $scope.$watch('filters', function(newVal, oldVal) {
    if(newVal !== oldVal) {
      // call with updated filters
    }
  });

  // ctrl watch ?
  $scope.$watch('filters.info', function(newVal, oldVal) {
    if(newVal !== oldVal) {
      // call with updated filters
    }
  });