Hi have a control of ComponentArt:Menu. 

this my code

<ClientEvents>

            <ItemSelect EventHandler="contextMenuClickHandler" />

        </ClientEvents>

but on client click I got hte javascript error

Unable to get value of the property 'ContextData': object is null or undefined 

this is my code:

  function contextMenuClickHandler(menuItem)

{

var contextDataNode = menuItem.ParentMenu.ContextData; 

var name = contextDataNode.substring(contextDataNode.indexOf('|')+1,contextDataNode.lastIndexOf('|'));

var id = contextDataNode.substring(contextDataNode.lastIndexOf('|')+1);

..........

........

}