A directive object can provide several hook functions,
bind: This occurs once the directive is attached to the element.
inserted: This hook occurs once the element is inserted into the parent DOM.
update: This hook is called when the element updates, but children haven't been updated yet.
componentUpdated: This hook is called once the component and the children have been updated.
unbind: This hook is called only once when the directive is removed.
Note: There are several arguments that can be passed to the above hooks.