Separator
The Separator control displays a line between items or groups of items.

Add Separator
Use the add() method of TreeCollection to add a separator between Ribbon controls:
ribbon.data.add({
type:"separator"
});
Related sample: Ribbon. Separator
Properties
Check the list of properties that you can set in the configuration object of a Separator control.
Show and hide Separator
Use the methods of Ribbon to show and hide a Separator control by its ID:
ribbon.showItem(id);
ribbon.hideItem(id);