A callback method that is invoked immediately after the default change detector has checked data-bound properties if at least one has changed, and before the view and content children are checked.
The changed properties.
A callback method that performs custom clean-up, invoked immediately before a directive, pipe, or service instance is destroyed.
A callback method that is invoked immediately after Angular has completed initialization of all of the directive's content. It is invoked only once when the directive is instantiated.