$watchGroup vs $watchCollection?

Question

There\'re 2 ways to watch a group of variables in Angular. But what\'s the difference between them?

They both seem to do shallow watches. Are there situations where one

Answer 1

Here's an example of where you'd use each one.

$scope.data = ['Abc', 'Bcd', 'Cde', 'Def'];
$scope.$watchCollection('data', function(){...});
// responds to changes within $scope.data
// The following line will trigger the watch function:
$scope.data[0] = 'FOO';

-

$scope.data = ['Abc', 'Bcd', 'Cde', 'Def'];
$scope.$watchGroup('data', function(){...});
// responds to changes on the properties (or functions, etc.)
// Any angular expression can be used in $scope.data
// The following line will trigger the watch function:
$scope.Abc = 'FOO';