Here is the solution for two common requirements for iewc treeview.
1. How to prevent postback when user is expanding, collapsing, checking or unchecking the treeview? (This is an example for oncheck. You can use other events too like onclick)
A) TreeView1.Attributes(“oncheck”) = “return Treeview_Hijack_OnCheck();” to your page_load()
Be aware that although this will prevent postbacks, but server side DOM for the treeview will no more give you a reliable value for node.checked property. In this case there is no utility of the above example, but its just a way to prevent postbacks, u can do the same for clicks, expands or any other event of the tree.
2. If you want to retain your postbacks but want a good user experience so that the page doesnt keep loading everytime you click or check a node then just turn Smartnavigation for your page on. You will like the results.