using javascript with multiple user controls

When using the same user control multiple times in the same page, accessing the user controls with javascript may be problematic, since locating a specific user control (i mean to seperate the user controls from each other) is a bit tricky.
In my condition, i solved by using a prefix as follows:

1:  function RowSelectionChanged(sender, eventArgs) {  
2:    if (sender != null) {  
3:      // to access a component in this user control  
4:      var prefix = sender.ClientID.substring(0, sender.ClientID.lastIndexOf("_"));  
5:      var param1= document.getElementById( prefix + '<%= "_LabelParam1" %>').value;  
6:      // to access a component in the main page  
7:      var prefixMainPage = sender.ClientID.substring(0, sender.ClientID.lastIndexOf("MyUserControl"));  
8:      var param2= document.getElementById(prefixAnaSayfa + '<%= "HiddenParam"%>').value;  
9:    }  
10:  }  

several possible resolutions proposed in: http://stackoverflow.com/questions/562152/multiple-user-controls-and-javascript, http://stackoverflow.com/questions/2533573/using-getelementbyid-inside-user-control