The ASPxHtmlEditor allows you to access and modify the currently selected content on the client side. To access the selection, use the editor's ASPxClientHtmlEditor.GetSelection client function, which returns an ASPxClientHtmlEditorSelection class instance. With methods of this class, you can perform your tasks on the selection. For example, to change the case of the selected text, you can use the ASPxClientHtmlEditorSelection.GetElements client function to access the selection's HTML elements (XML DOM nodes), retrieve references to text nodes using these elements and update the case as necessary.
The selection API is available only in the Design View.