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DropDownTree Client Side Event in ASP.NET
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When you want to create a DropDownTree structure into your project, you should apply the Kettic DropDownTree control, which combines a dropdown together with a tree control. By customizing corresponding behaviors, users will be enabled to create a DropDownTree that is tailored to your requirements. Here we have listed a few client-side events that might be useful for you.
OnClientLoad: This event is used to call the client-side event handler once the Kettic DropDownTree has been completely initialized on the client-side. It receives a reference to the client-side dropdowntree object, so you can use it to perform initialization on your own. Please note that you can only proceed with further customization after this event handler is loaded.
OnClientDropDownOpening: Fire this client-side event so you can open the Kettic DropDownTree and adjust / modify it later on. Note that you can cancel this event by setting true to args.set_cancel.
OnClientDropDownClosing: You can fire this client-side event to close a DropDownTree when you’re done with editing or customizing. It can only be used before a DropDownTree is closed.
OnClientDropDownClosed: If a DropDownTree is already closed, this client-side event can be fired, and it cannot be reversed once fired.
OnClientEntryAdding: When you want to add an entry, this client-side event can be fired so that a brand new entry is created directly. Additionally, you can cancel this event simply by setting args.set_cancel to true.
OnClientEntryAdded: If an entry has been added already, you should use this client-side event instead. Note that this event cannot be cancelled. If you want to remove an entry, try the following client-side event.
OnClientEntryRemoving: This client-side event can only be fired when you want to remove an entry from the Entry area. Don’t worry if you have removed an entry by mistake, because this event can be easily cancelled. All you have to do is simply set true to the args.set_cancel from the handler, and the removed entry can be regained.
OnClientEntryRemoved: Fire this client-side event after an entry has been removed from the entry area. You cannot cancel this event once it is fired.
OnClientClearButtonClicking: When you click the Clear button in the DropDownTree entry area, this client-side event is fired right away. You can also cancel this event by setting true to args.set_cancel.
OnClientClearButtonClicked: This client-side event is fired after you have clicked the clear button in the DropDownTree. This event cannot be cancelled either.
Here are the Javascript codes for the DropDownTree client-side event introduced above:
<script type="text/javascript">
function logEvent(eventInfo) {
var EventLogConsole = $get("<%=EventLogConsole1.ClientID%>");
EventLogConsole.innerHTML += eventInfo + "<br/>";
function onDropDownOpening(sender) {
logEvent("Drop Down opening");

function onDropDownOpened(sender) {
logEvent("Drop Down opened");

function onDropDownClosing(sender) {
logEvent("Drop Down closing");

function onDropDownClosed(sender) {
logEvent("Drop Down closed");

function onEntryAdding(sender, eventArgs) {
logEvent("Drop Down EntryAdding, the '" + eventArgs.get_entry().get_text() + "' entry will be added.");
function onEntryAdded(sender, eventArgs) {
logEvent("Drop Down EntryAdded");
function onEntryRemoving(sender, eventArgs) {
logEvent("Drop Down EntryRemoving the '" + eventArgs.get_entry().get_text() + "' entry will be removed.");
function onEntryRemoved(sender, eventArgs) {
logEvent("Drop Down EntryRemoved ");