- Integrate $scope.$watch to watch Controller properties
- Use a deep $watch to observe deep changes
- Write a $watchCollection method for better shallow performance
In this repo, we've got a few fields to fill out for a user's information: their username and their country's short name (abbreviation), full name, and population.
Using $scope.$watch, check whenever the username gets updated.
Deep watch the whole country object to see when any value in it changes (including the country's short and full names).
Use $watchCollection to see only when the country's full and short names are updated.