ASP.NET MVC Controls | ComponentOne
In This Topic
    TreeView Class
    In This Topic
    File
    wijmo.nav.js
    Module
    wijmo.nav
    Base Class
    Control

    The TreeView control displays a hierarchical list of TreeNode objects which may contain text, checkboxes, images, or arbitrary HTML content.

    A TreeView is typically used to display the headings in a document, the entries in an index, the files and directories on a disk, or any other kind of information that might usefully be displayed as a hierarchy.

    After creating a TreeView, you will typically set the following properties:

    1. itemsSource: an array that contains the data to be displayed on the tree.
    2. displayMemberPath: the name of the data item property that contains the text to display on the nodes (defaults to 'header'), and
    3. childItemsPath: the name of the data item property that contains the node's child items (defaults to 'items').

    The TreeView control supports the following keyboard commands:

    Key Combination Action
    Up/Down Select the previous/next visible node
    Left Collapse the selected node if it has child nodes, select the parent node otherwise
    Right Expand the selected node if it has child nodes
    Home/End Select the first/last visible nodes
    Space Toggle the checkbox in the current node (see the showCheckboxes property)
    Other characters Search for nodes that contain the text typed (multi-character auto-search)

    The example below builds a simple tree and allows you to see the effect of the TreeView's main properties:

    {@sample Nav/TreeView/Behavior/purejs Example}

    Constructor

    Properties

    Methods

    Events

    Constructor

    constructor

    constructor(element: any, options: any): TreeView
    

    Initializes a new instance of the TreeView class.

    Parameters
    • element: any

      The DOM element that hosts the control, or a CSS selector for the host element (e.g. '#theCtrl').

    • options: any

      The JavaScript object containing initialization data for the control.

    Returns
    TreeView

    Properties

    allowDragging

    Gets or sets a value that determines whether users can drag and drop nodes within the TreeView.

    The default value for this property is **false**.

    Type
    boolean

    autoCollapse

    Gets or sets a value that determines if sibling nodes should be collapsed when a node is expanded.

    The default value for this property is **true**, because in most cases collapsing nodes that are not in use helps keep the UI clean.

    Type
    boolean

    checkedItems

    Gets an array containing the items that are currently checked.

    The array returned includes only items that have no children. This is because checkboxes in parent items are used to check or uncheck the child items.

    See also the showCheckboxes property and the checkedItemsChanged event.

    For example:

    import { TreeView } from '@mescius/wijmo.nav';
    var treeViewChk = new TreeView('#gsTreeViewChk', {
       displayMemberPath: 'header',
       childItemsPath: 'items',
       showCheckboxes: true,
       itemsSource: items,
       checkedItemsChanged: function (s, e) {
           var items = s.checkedItems,
               msg = '';
           if (items.length) {
               msg = '<p><b>Selected Items:</b></p><ol>\r\n';
               for (var i = 0; i < items.length; i++) {
                   msg += '<li>' + items[i].header + '</li>\r\n';
               }
               msg += '</ol>';
           }
           document.getElementById('gsTreeViewChkStatus').innerHTML = msg;
       }
    });
    

    Type
    any[]

    checkedMemberPath

    Gets or sets the name of the property (or properties) to bind to the node's checked state.

    See also the showCheckboxes property and the checkedItemsChanged event.

    Type
    string

    checkOnClick

    Gets or sets a value that determines whether to toggle checkboxes when the user clicks the node header.

    The default value for this property is **false**, which causes checkboxes to be toggled only when the user clicks the checkbox itself (not the node header).

    See also the showCheckboxes property and the checkedItemsChanged event.

    Type
    boolean

    childItemsPath

    Gets or sets the name of the property (or properties) that contains the child items for each node.

    The default value for this property is the string **"items"**.

    In most cases, the property that contains the child items is the same for all data items on the tree. In these cases, set the childItemsPath to that name.

    In some cases, however, items at different levels use different properties to store their child items. For example, you could have a tree with categories, products, and orders. In that case, you would set the childItemsPath to an array such as this:

    // categories have products, products have orders:
    tree.childItemsPath = [ 'Products', 'Orders' ];
    
    Type
    string

    collapseOnClick

    Gets or sets a value that determines whether to collapse expanded nodes when the user clicks the node header.

    The default value for this property is **false**.

    When this property is set to **false**, users have to click the expand/collapse icons to collapse the node. Clicking the node header will select the node if it is not selected, and will start editing the node if it is selected (and if the isReadOnly property is set to false).

    See also the expandOnClick property.

    Type
    boolean

    collapseWhenDisabled

    Gets or sets a value that determines whether nodes should be collapsed when they are disabled.

    The default value for this property is **true**.

    Type
    boolean

     

    Static controlTemplate

    Gets or sets the template used to instantiate TreeView controls.

    Type
    any

    displayMemberPath

    Gets or sets the name of the property (or properties) to use as the visual representation of the nodes.

    The default value for this property is the string **"header"**.

    In most cases, the property that contains the node text is the same for all data items on the tree. In these cases, set the displayMemberPath to that name.

    In some cases, however, items at different levels use different properties to represent them. For example, you could have a tree with categories, products, and orders. In that case, you might set the displayMemberPath to an array such as this:

    // categories, products, and orders have different headers:
    tree.displayMemberPath = [ 'CategoryName', 'ProductName', 'OrderID' ];
    
    Type
    string

    expandOnClick

    Gets or sets a value that determines whether to expand collapsed nodes when the user clicks the node header.

    The default value for this property is **true**.

    When this property is set to **false**, users have to click the expand/collapse icons to collapse the node. Clicking the node header will select the node if it is not selected, and will start editing the node if it is selected (and if the isReadOnly property is set to false).

    See also the collapseOnClick property.

    Type
    boolean

    expandOnLoad

    Gets or sets a value that determines whether to automatically expand the first node when the tree is loaded.

    The default value for this property is **true**. If you set it to false, all nodes will be initially collapsed.

    Type
    boolean

    hostElement

    Gets the DOM element that is hosting the control.

    Inherited From
    Control
    Type
    HTMLElement

    imageMemberPath

    Gets or sets the name of the property (or properties) to use as a source of images for the nodes.

    The default value for this property is an empty string, which means no images are added to the nodes.

    Type
    string

    isAnimated

    Gets or sets a value that indicates whether to use animations when expanding or collapsing nodes.

    The default value for this property is **true**.

    Type
    boolean

    isContentHtml

    Gets or sets a value indicating whether items are bound to plain text or HTML.

    The default value for this property is **false**.

    Type
    boolean

    isDisabled

    Gets or sets a value that determines whether the control is disabled.

    Disabled controls cannot get mouse or keyboard events.

    Inherited From
    Control
    Type
    boolean

    isReadOnly

    Gets or sets a value that determines whether users can edit the text in the nodes.

    When the isReadOnly property is set to false, users may edit the content of the tree nodes by typing directly into the nodes. The F2 key can also be used to enter edit mode with the whole node content selected.

    You may customize the editing behavior using the following methods and events:

    **Methods**: startEditing, finishEditing.

    **Events**: nodeEditStarting, nodeEditStarted, nodeEditEnding, nodeEditEnded.

    The default value for this property is **true**.

    Type
    boolean

    isTouching

    Gets a value that indicates whether the control is currently handling a touch event.

    Inherited From
    Control
    Type
    boolean

    isUpdating

    Gets a value that indicates whether the control is currently being updated.

    Inherited From
    Control
    Type
    boolean

    itemsSource

    Gets or sets the array that contains the TreeView items.

    TreeView #see:itemsSource arrays usually have a hierarchical structure with items that contain child items. There is no fixed limit to the depth of the items.

    For example, the array below would generate a tree with three top-level nodes, each with two child nodes:

    import { TreeView } from '@mescius/wijmo.nav';
    var tree = new TreeView('#treeView', {
        displayMemberPath: 'header',
        childItemsPath: 'items',
        itemsSource: [
            { header: '1 first', items: [
                { header: '1.1 first child' },
                { header: '1.2 second child' },
            ] },
            { header: '2 second', items: [
                { header: '3.1 first child' },
                { header: '3.2 second child' },
            ] },
            { header: '3 third', items: [
                { header: '3.1 first child' },
                { header: '3.2 second child' },
            ] }
        ]
    });
    

    Type
    any[]

    lazyLoadFunction

    Gets or sets a function that loads child nodes on demand.

    The lazyLoadFunction takes two parameters: the node being expanded and a callback to be invoked when the data becomes available.

    The callback function tells the TreeView that the node loading process has been completed. It should always be called, even if there are errors when loading the data.

    For example:

    import { TreeView } from '@mescius/wijmo.nav';
    var treeViewLazyLoad = new TreeView('#treeViewLazyLoad', {
       displayMemberPath: 'header',
       childItemsPath: 'items',
       itemsSource: [ // start with three lazy-loaded nodes
           { header: 'Lazy Node 1', items: []},
           { header: 'Lazy Node 2', items: [] },
           { header: 'Lazy Node 3', items: [] }
       ],
       lazyLoadFunction: function (node, callback) {
           setTimeout(function () { // simulate http delay
               var result = [ // simulate result
                   { header: 'Another lazy node...', items: [] },
                   { header: 'A non-lazy node without children' },
                   { header: 'A non-lazy node with child nodes', items: [
                     { header: 'hello' },
                     { header: 'world' }
                   ]}
               ];
               callback(result); // return result to control
           }, 2500); // simulated 2.5 sec http delay
       }
    });
    

    Trees with lazy-loaded nodes have some restrictions: their nodes may not have checkboxes (see the showCheckboxes property) and the collapseToLevel method will not expand collapsed nodes that have not been loaded yet.

    Type
    ILazyLoad

    nodes

    Gets an array of TreeNode objects representing the nodes currently loaded.

    Type
    TreeNode[]

    rightToLeft

    Gets a value indicating whether the control is hosted in an element with right-to-left layout.

    Inherited From
    Control
    Type
    boolean

    selectedItem

    Gets or sets the data item that is currently selected.

    Type
    any

    selectedNode

    Gets or sets the TreeNode that is currently selected.

    Type
    TreeNode

    selectedPath

    Gets an array containing the text of all nodes from the root to the currently selected node.

    Type
    string[]

    showCheckboxes

    Gets or sets a value that determines whether the TreeView should add checkboxes to nodes and manage their state.

    This property can be used only on trees without lazy-loaded nodes (see the lazyLoadFunction property).

    See also the checkedItems property and checkedItemsChanged event.

    The default value for this property is **false**.

    Type
    boolean

    tabOrder

    Gets or sets a value of the **tabindex** attribute associated with the control.

    **tabindex** attribute value can be defined statically for a Wijmo control by specifying it on the control's host HTML element. But this value can't be changed later during application lifecycle, because Wijmo controls have complex structure, and the control may need to propagate this attribute value to its internal element to work properly.

    Because of this, to read or change control's **tabindex** dynamically, you should do it using this property.

    Inherited From
    Control
    Type
    number

    totalItemCount

    Gets the total number of items in the tree.

    Type
    number

    Methods

    addChildNode

    addChildNode(index: number, dataItem: any): TreeNode
    

    Adds a child node at a specific position.

    Parameters
    • index: number

      Index of the new child node.

    • dataItem: any

      Data item used to create the new node.

    Returns
    TreeNode

    addEventListener

    addEventListener(target: EventTarget, type: string, fn: any, capture?: boolean, passive?: boolean): void
    

    Adds an event listener to an element owned by this Control.

    The control keeps a list of attached listeners and their handlers, making it easier to remove them when the control is disposed (see the dispose and removeEventListener methods).

    Failing to remove event listeners may cause memory leaks.

    The passive parameter is set to false by default, which means the event handler may call event.preventDefault(). If you are adding passive handlers to touch or wheel events, setting this parameter to true will improve application performance.

    For details on passive event listeners, please see Improving scrolling performance with passive listeners.

    Parameters
    • target: EventTarget

      Target element for the event.

    • type: string

      String that specifies the event.

    • fn: any

      Function to execute when the event occurs.

    • capture: boolean
    Optional

    Whether the listener should be handled by the control before it is handled by the target element.

    Indicates that the handler will never call preventDefault().

    Inherited From
    Control
    Returns
    void

    applyTemplate

    applyTemplate(classNames: string, template: string, parts: Object, namePart?: string): HTMLElement
    

    Applies the template to a new instance of a control, and returns the root element.

    This method should be called by constructors of templated controls. Therefore, this method is not available. It is responsible for binding the template parts to the corresponding control members.

    For example, the code below applies a template to an instance of an InputNumber control. The template must contain elements with the 'wj-part' attribute set to 'input', 'btn-inc', and 'btn-dec'. The control members '_tbx', '_btnUp', and '_btnDn' will be assigned references to these elements.

    this.applyTemplate('wj-control wj-inputnumber', templateString, {
      _tbx: 'input',
      _btnUp: 'btn-inc',
      _btnDn: 'btn-dec'
    }, 'input');
    
    ```

    Parameters
    • classNames: string

      Names of classes to add to the control's host element.

    • template: string

      An HTML string that defines the control template.

    • parts: Object

      A dictionary of part variables and their names.

    • namePart: string Optional

      Name of the part to be named after the host element. This determines how the control submits data when used in forms.

    Inherited From
    Control
    Returns
    HTMLElement

    beginUpdate

    beginUpdate(): void
    

    Suspends notifications until the next call to endUpdate.

    Inherited From
    Control
    Returns
    void

    checkAllItems

    checkAllItems(check: boolean): void
    

    Checks or unchecks all checkboxes on the tree.

    Parameters
    • check: boolean

      Whether to check or uncheck all checkboxes.

    Returns
    void

    collapseToLevel

    collapseToLevel(level: number): void
    

    Collapses all the tree items to a given level.

    This method will typically expand or collapse multiple nodes at once. But it will not perform lazy-loading on any nodes, so collapsed nodes that must be lazy-loaded will not be expanded.

    Parameters
    • level: number

      Maximum node level to show.

    Returns
    void

    containsFocus

    containsFocus(): boolean
    

    Checks whether this control contains the focused element.

    Inherited From
    Control
    Returns
    boolean

    deferUpdate

    deferUpdate(fn: Function): void
    

    Executes a function within a beginUpdate/endUpdate block.

    The control will not be updated until the function has been executed. This method ensures endUpdate is called even if the function throws an exception.

    Parameters
    Inherited From
    Control
    Returns
    void

    dispose

    dispose(): void
    

    Disposes of the control by removing its association with the host element.

    The dispose method automatically removes any event listeners added with the addEventListener method.

    Calling the dispose method is important in applications that create and remove controls dynamically. Failing to dispose of the controls may cause memory leaks.

    Inherited From
    Control
    Returns
    void

    Static disposeAll

    disposeAll(e?: HTMLElement): void
    

    Disposes of all Wijmo controls contained in an HTML element.

    Parameters
    Inherited From
    Control
    Returns
    void

    endUpdate

    endUpdate(): void
    

    Resumes notifications suspended by calls to beginUpdate.

    Inherited From
    Control
    Returns
    void

    finishEditing

    finishEditing(cancel?: boolean): boolean
    

    Commits any pending edits and exits edit mode.

    Parameters
    • cancel: boolean Optional

      Whether pending edits should be canceled or committed.

    Returns
    boolean

    focus

    focus(): void
    

    Sets the focus to this control.

    Inherited From
    Control
    Returns
    void

    Static getControl

    getControl(element: any): Control
    

    Gets the control that is hosted in a given DOM element.

    Parameters
    • element: any

      The DOM element that hosts the control, or a CSS selector for the host element (e.g. '#theCtrl').

    Inherited From
    Control
    Returns
    Control

    getFirstNode

    getFirstNode(visible?: boolean, enabled?: boolean): TreeNode
    

    Gets a reference to the first TreeNode in the TreeView.

    Parameters
    • visible: boolean Optional

      Whether to return only visible nodes (whose ancestors are not collapsed).

    • enabled: boolean Optional

      Whether to return only enabled nodes (whose ancestors are not disabled).

    Returns
    TreeNode

    getLastNode

    getLastNode(visible?: boolean, enabled?: boolean): TreeNode
    

    Gets a reference to the last TreeNode in the TreeView.

    Parameters
    • visible: boolean Optional

      Whether to return only visible nodes (whose ancestors are not collapsed).

    • enabled: boolean Optional

      Whether to return only enabled nodes (whose ancestors are not disabled).

    Returns
    TreeNode

    getNode

    getNode(item: any): TreeNode
    

    Gets the TreeNode object representing a given data item.

    Parameters
    • item: any

      The data item to look for.

    Returns
    TreeNode

    getTemplate

    getTemplate(): string
    

    Gets the HTML template used to create instances of the control.

    This method traverses up the class hierarchy to find the nearest ancestor that specifies a control template. For example, if you specify a prototype for the ComboBox control, which does not specify a template, it will override the template defined by the DropDown base class (the nearest ancestor that does specify a template).

    Inherited From
    Control
    Returns
    string

    initialize

    initialize(options: any): void
    

    Initializes the control by copying the properties from a given object.

    This method allows you to initialize controls using plain data objects instead of setting the value of each property in code.

    For example:

    grid.initialize({
      itemsSource: myList,
      autoGenerateColumns: false,
      columns: [
        { binding: 'id', header: 'Code', width: 130 },
        { binding: 'name', header: 'Name', width: 60 } 
      ]
    });



    // is equivalent to grid.itemsSource = myList; grid.autoGenerateColumns = false; // etc.

    The initialization data is type-checked as it is applied. If the initialization object contains unknown property names or invalid data types, this method will throw.

    Parameters
    • options: any

      Object that contains the initialization data.

    Inherited From
    Control
    Returns
    void

    invalidate

    invalidate(fullUpdate?: boolean): void
    

    Invalidates the control causing an asynchronous refresh.

    Parameters
    • fullUpdate: boolean Optional

      Whether to update the control layout as well as the content.

    Inherited From
    Control
    Returns
    void

    Static invalidateAll

    invalidateAll(e?: HTMLElement): void
    

    Invalidates all Wijmo controls contained in an HTML element.

    Use this method when your application has dynamic panels that change the control's visibility or dimensions. For example, splitters, accordions, and tab controls usually change the visibility of its content elements. In this case, failing to notify the controls contained in the element may cause them to stop working properly.

    If this happens, you must handle the appropriate event in the dynamic container and call the invalidateAll method so the contained Wijmo controls will update their layout information properly.

    Parameters
    • e: HTMLElement Optional

      Container element. If set to null, all Wijmo controls on the page will be invalidated.

    Inherited From
    Control
    Returns
    void

    loadTree

    loadTree(preserveOutlineState?: boolean): void
    

    Loads the tree using data from the current itemsSource.

    Parameters
    • preserveOutlineState: boolean Optional

      Whether to preserve the outline state when loading the tree data. Defaults to false.

    Returns
    void

    onCheckedItemsChanged

    onCheckedItemsChanged(e?: EventArgs): void
    

    Raises the checkedItemsChanged event.

    Parameters
    Returns
    void

    onDragEnd

    onDragEnd(e?: EventArgs): void
    

    Raises the dragEnd event.

    Parameters
    Returns
    void

    onDragOver

    onDragOver(e: TreeNodeDragDropEventArgs): boolean
    

    Raises the dragOver event.

    Parameters
    Returns
    boolean

    onDragStart

    onDragStart(e: TreeNodeEventArgs): boolean
    

    Raises the dragStart event.

    Parameters
    Returns
    boolean

    onDrop

    onDrop(e: TreeNodeDragDropEventArgs): boolean
    

    Raises the drop event.

    Parameters
    Returns
    boolean

    onFormatItem

    onFormatItem(e: FormatNodeEventArgs): void
    

    Raises the formatItem event.

    Parameters
    Returns
    void

    onGotFocus

    onGotFocus(e?: EventArgs): void
    

    Raises the gotFocus event.

    Parameters
    Inherited From
    Control
    Returns
    void

    onInvalidInput

    onInvalidInput(e: CancelEventArgs): void
    

    Raises the invalidInput event.

    If the event handler cancels the event, the control will keep the invalid input and the focus.

    Parameters
    Inherited From
    Control
    Returns
    void

    onIsCheckedChanged

    onIsCheckedChanged(e: TreeNodeEventArgs): void
    

    Raises the isCheckedChanged event.

    Parameters
    Returns
    void

    onIsCheckedChanging

    onIsCheckedChanging(e: TreeNodeEventArgs): boolean
    

    Raises the isCheckedChanging event.

    Parameters
    Returns
    boolean

    onIsCollapsedChanged

    onIsCollapsedChanged(e: TreeNodeEventArgs): void
    

    Raises the isCollapsedChanged event.

    Parameters
    Returns
    void

    onIsCollapsedChanging

    onIsCollapsedChanging(e: TreeNodeEventArgs): boolean
    

    Raises the isCollapsedChanging event.

    Parameters
    Returns
    boolean

    onItemClicked

    onItemClicked(e?: EventArgs): void
    

    Raises the itemClicked event.

    Parameters
    Returns
    void

    onItemsSourceChanged

    onItemsSourceChanged(e?: EventArgs): void
    

    Raises the itemsSourceChanged event.

    Parameters
    Returns
    void

    onLoadedItems

    onLoadedItems(e?: EventArgs): void
    

    Raises the loadedItems event.

    Parameters
    Returns
    void

    onLoadingItems

    onLoadingItems(e?: CancelEventArgs): boolean
    

    Raises the loadingItems event.

    Parameters
    Returns
    boolean

    onLostFocus

    onLostFocus(e?: EventArgs): void
    

    Raises the lostFocus event.

    Parameters
    Inherited From
    Control
    Returns
    void

    onNodeEditEnded

    onNodeEditEnded(e: TreeNodeEventArgs): void
    

    Raises the nodeEditEnded event.

    Parameters
    Returns
    void

    onNodeEditEnding

    onNodeEditEnding(e: TreeNodeEventArgs): boolean
    

    Raises the nodeEditEnding event.

    Parameters
    Returns
    boolean

    onNodeEditStarted

    onNodeEditStarted(e: TreeNodeEventArgs): void
    

    Raises the nodeEditStarted event.

    Parameters
    Returns
    void

    onNodeEditStarting

    onNodeEditStarting(e: TreeNodeEventArgs): boolean
    

    Raises the nodeEditStarting event.

    Parameters
    Returns
    boolean

    onRefreshed

    onRefreshed(e?: EventArgs): void
    

    Raises the refreshed event.

    Parameters
    Inherited From
    Control
    Returns
    void

    onRefreshing

    onRefreshing(e?: EventArgs): void
    

    Raises the refreshing event.

    Parameters
    Inherited From
    Control
    Returns
    void

    onSelectedItemChanged

    onSelectedItemChanged(e?: EventArgs): void
    

    Raises the selectedItemChanged event.

    Parameters
    Returns
    void

    refresh

    refresh(fullUpdate?: boolean): void
    

    Overridden to re-populate the tree.

    Parameters
    • fullUpdate: boolean Optional

      Indicates whether to update the control layout as well as the content.

    Returns
    void

    Static refreshAll

    refreshAll(e?: HTMLElement): void
    

    Refreshes all Wijmo controls contained in an HTML element.

    This method is similar to invalidateAll, except the controls are updated immediately rather than after an interval.

    Parameters
    • e: HTMLElement Optional

      Container element. If set to null, all Wijmo controls on the page will be invalidated.

    Inherited From
    Control
    Returns
    void

    removeEventListener

    removeEventListener(target?: EventTarget, type?: string, fn?: any, capture?: boolean): number
    

    Removes one or more event listeners attached to elements owned by this Control.

    Parameters
    • target: EventTarget Optional

      Target element for the event. If null, removes listeners attached to all targets.

    • type: string Optional

      String that specifies the event. If null, removes listeners attached to all events.

    • fn: any Optional

      Handler to remove. If null, removes all handlers.

    • capture: boolean Optional

      Whether the listener is capturing. If null, removes capturing and non-capturing listeners.

    Inherited From
    Control
    Returns
    number

    startEditing

    startEditing(node?: TreeNode): boolean
    

    Starts editing a given TreeNode.

    Parameters
    • node: TreeNode Optional

      TreeNode to edit. If not provided, the currently selected node is used.

    Returns
    boolean

    Events

    checkedItemsChanged

    Occurs when the value of the checkedItems property changes.

    See also the showCheckboxes and checkOnClick properties.

    Arguments
    EventArgs

    dragEnd

    Occurs when the user finishes a drag/drop operation, either by dropping a node into a new location or by canceling the operation with the mouse or keyboard.

    Arguments
    EventArgs

    dragOver

    Occurs while the user drags a node over other nodes on the TreeView.

    This event only occurs if the allowDragging property is set to true.

    You may prevent drop operations over certain nodes and/or positions by setting the event's **cancel** parameter to true.

    Arguments
    TreeNodeDragDropEventArgs

    dragStart

    Occurs when the user starts dragging a node.

    This event only occurs if the allowDragging property is set to true.

    You may prevent nodes from being dragged by setting the event's **cancel** parameter to true.

    Arguments
    TreeNodeEventArgs

    drop

    Occurs when the user drops a on the TreeView.

    Arguments
    TreeNodeDragDropEventArgs

    formatItem

    Occurs when an element representing a node has been created.

    This event can be used to format nodes for display.

    The example below uses the **formatItem** event to add a "new" badge to the right of new items on the tree.

    import { TreeView } from '@mescius/wijmo.nav';
    var treeViewFmtItem = new TreeView('#treeViewFmtItem', {
        displayMemberPath: 'header',
        childItemsPath: 'items',
        itemsSource: items,
        formatItem: function (s, e) {
            if (e.dataItem.newItem) {
                let img = wijmo.createElement('<img style="margin-left:6px" src="resources/new.png"/>');
                e.element.appendChild(img);
            }
        }
    });
    
    

    Arguments
    FormatNodeEventArgs

    gotFocus

    Occurs when the control gets the focus.

    Inherited From
    Control
    Arguments
    EventArgs

    invalidInput

    Occurs when invalid input is detected.

    Invalid input may occur when the user types or pastes a value that cannot be converted to the proper type, or a value that is outside the valid range.

    If the event handler cancels the event, the control will retain the invalid content and the focus, so users can correct the error.

    If the event is not canceled, the control will ignore the invalid input and will retain the original content.

    Inherited From
    Control
    Arguments
    CancelEventArgs

    isCheckedChanged

    Occurs after the value of the isChecked property changes.

    Arguments
    TreeNodeEventArgs

    isCheckedChanging

    Occurs before the value of the isChecked property changes.

    Arguments
    TreeNodeEventArgs

    isCollapsedChanged

    Occurs after the value of the isCollapsed property changes.

    Arguments
    TreeNodeEventArgs

    isCollapsedChanging

    Occurs before the value of the isCollapsed property changes.

    Arguments
    TreeNodeEventArgs

    itemClicked

    Occurs when the user clicks an item or presses the Enter key and an item is selected.

    This event is typically used in navigation trees. Use the selectedItem property to get the item that was clicked.

    Arguments
    EventArgs

    itemsSourceChanged

    Occurs when the value of the itemsSource property changes.

    Arguments
    EventArgs

    loadedItems

    Occurs after the tree items have been generated.

    Arguments
    EventArgs

    loadingItems

    Occurs before the tree items are generated.

    Arguments
    CancelEventArgs

    lostFocus

    Occurs when the control loses the focus.

    Inherited From
    Control
    Arguments
    EventArgs

    nodeEditEnded

    Occurs after a TreeNode has exited edit mode.

    Arguments
    TreeNodeEventArgs

    nodeEditEnding

    Occurs before a TreeNode exits edit mode.

    Arguments
    TreeNodeEventArgs

    nodeEditStarted

    Occurs after a TreeNode has entered edit mode.

    Arguments
    TreeNodeEventArgs

    nodeEditStarting

    Occurs before a TreeNode enters edit mode.

    Arguments
    TreeNodeEventArgs

    refreshed

    Occurs after the control has refreshed its contents.

    Inherited From
    Control
    Arguments
    EventArgs

    refreshing

    Occurs when the control is about to refresh its contents.

    Inherited From
    Control
    Arguments
    EventArgs

    selectedItemChanged

    Occurs when the value of the selectedItem property changes.

    Arguments
    EventArgs