CED.

 

You can use the following code to get the editor:
 
var editor1=document.getElementById('<%=Editor1.ClientID%>');

var editor1doc = editor1.GetDocument();

Now you can get the selection and write your JavaScript code:
 

For example:

 

if(editor1doc.selection.type=='Control')
{
    // put your code here...
       ......... 

}