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

The $watchCollection() function is a sort-of mid-ground between the two $watch() configurations above. It's more in-depth than the vanilla $watch() function; but, it's not nearly as expensive as the deep-equality $watch() function. Like the $watch() function, the $watchCollection() works by comparing physical object references; however, unlike the $watch() function, the $watchCollection() goes one-level deep and performs an additional, shallow reference check of the top level items in the collection.

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