var treeview = "";
function ClientNodeClicked(sender, eventArgs) {
    var node = eventArgs.get_node();
    if (node.get_level() == 0  && !node.get_expanded()) {
        treeCollapseAllNodes();
    }
    if (!node.get_expanded()) {
        node.toggle();
    }
}


function treeCollapseAllNodes() {
    var treeView = $find(treeview);
    var nodes = treeView.get_allNodes();

    for (var i = 0; i < nodes.length; i++) {
        if (nodes[i].get_nodes() != null) {
            nodes[i].collapse();
        }
    }
}