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.
canExecute : boolean
Gets whether this command can currently be executed. This property is observable.