A callback method that is invoked immediately after the
default change detector has checked the directive's
data-bound properties for the first time,
and before any of the view or content children have been checked.
It is invoked only once when the directive is instantiated.
A callback method that is invoked immediately after the default change detector has checked the directive's data-bound properties for the first time, and before any of the view or content children have been checked. It is invoked only once when the directive is instantiated.