# OnClientContextMenuShowing

The **OnClientContextMenuShowing** client-side event occurs just prior to opening a context menu. If the event is canceled, the **OnClientContextMenuShown** event does not fire.

The event handler receives parameters:

1. The **TreeView** instance that fired the event.

2. Event arguments with functions:

* **get_menu()** retrieves a reference to the context menu.

* **get_node()** retrieves a reference to the clicked on node.

* **get_domEvent()** retrieves a DOM element that represents the context menu.

* **set_cancel()** call this function to specify whether the event should be canceled (true) or not (false).

The example below displays the menu id and the node that the context menu is being opened for. The event is canceled if the menu is being opened for node "Printers".

```ASPNET
<telerik:RadTreeView RenderMode="Lightweight" ID="RadTreeView1" runat="server" OnClientContextMenuShowing="ClientContextMenuShowing">
    <Nodes>
        <telerik:RadTreeNode runat="server" ExpandMode="ClientSide" Text="Search" ImageUrl="~/images/search.ico"
            Expanded="True" Value="1">
            <Nodes>
                <telerik:RadTreeNode runat="server" ExpandMode="ClientSide" Text="Documents" ImageUrl="~/images/search4doc.ico"
                    Category="NoDragging">
                </telerik:RadTreeNode>
                <telerik:RadTreeNode runat="server" ExpandMode="ClientSide" Text="Files" ImageUrl="~/images/search4Files.ico">
                </telerik:RadTreeNode>
                <telerik:RadTreeNode runat="server" ExpandMode="ClientSide" Text="People" ImageUrl="~/images/search4people.ico">
                </telerik:RadTreeNode>
                <telerik:RadTreeNode runat="server" ExpandMode="ClientSide" Text="Printers" ImageUrl="~/images/search4printer.ico">
                </telerik:RadTreeNode>
                <telerik:RadTreeNode runat="server" ExpandMode="ClientSide" Text="Web" ImageUrl="~/images/searchweb.ico"
                    Category="NonCheckable">
                </telerik:RadTreeNode>
                <telerik:RadTreeNode runat="server" ExpandMode="ServerSide" Text="Recent Searches">
                </telerik:RadTreeNode>
                <telerik:RadTreeNode runat="server" ExpandMode="ServerSideCallBack" Text="Network Locations"
                    ContextMenuID="SearchMenu">
                </telerik:RadTreeNode>
            </Nodes>
        </telerik:RadTreeNode>
    </Nodes>
    <ContextMenus>
        <telerik:RadTreeViewContextMenu ID="SearchMenu" runat="server" Flow="Horizontal">
            <DefaultGroupSettings ExpandDirection="Auto" Flow="Vertical" />
            <Items>
                <telerik:RadMenuItem runat="server" ExpandMode="ClientSide" Text="Local Search">
                    <GroupSettings ExpandDirection="Auto" Flow="Vertical" />
                </telerik:RadMenuItem>
                <telerik:RadMenuItem runat="server" ExpandMode="ClientSide" Text="Search Network">
                    <GroupSettings ExpandDirection="Auto" Flow="Vertical" />
                </telerik:RadMenuItem>
            </Items>
        </telerik:RadTreeViewContextMenu>
    </ContextMenus>
</telerik:RadTreeView>
```

```JavaScript
function ClientContextMenuShowing(sender, eventArgs) {
	var node = eventArgs.get_node();
	var menu = eventArgs.get_menu();
	var domEvent = eventArgs.get_domEvent();

	alert("Showing menu " + menu.get_id() +
			" for node " +
			node.get_text());

	if (node.get_text() == "Printers") {
		eventArgs.set_cancel(true);
	}
}
```

## See Also

* [RadTreeNode](https://www.telerik.com/products/aspnet-ajax/documentation/controls/treeview/client-side-programming/objects/radtreenode)

* [RadTreeNode](https://www.telerik.com/products/aspnet-ajax/documentation/controls/treeview/client-side-programming/objects/radtreenode)

* [OnClientContextMenuItemClicked](https://www.telerik.com/products/aspnet-ajax/documentation/controls/treeview/client-side-programming/events/onclientcontextmenuitemclicked)

* [OnClientContextMenuItemClicking](https://www.telerik.com/products/aspnet-ajax/documentation/controls/treeview/client-side-programming/events/onclientcontextmenuitemclicking)

* [OnClientContextMenuShown](https://www.telerik.com/products/aspnet-ajax/documentation/controls/treeview/client-side-programming/events/onclientcontextmenushown)