A Command is a function with an extra
canExecuteobservable property to determine whether the command can be executed. When executed, a Command function will check the value of
canExecuteand throw if false. This type describes an interface and is not intended to be instantiated directly. See
createCommandto create a command from a function.
afterExecute : Event
Gets an event which is raised after the command executes, the event is raised with the return value of the command as its only parameter.
beforeExecute : Event
Gets an event which is raised before the command executes, the event is raised with an object containing two properties: a
cancelproperty, which if set to false by the listener will prevent the command from being executed, and an
argsproperty, which is the array of arguments being passed to the command.
Gets whether this command can currently be executed. This property is observable.