# Wijmo_Input.Listbox ## Content

ListBox Class

The ListBox control displays a list of items which may contain plain text or HTML, and allows users to select items with the mouse or the keyboard.

Use the ListBox.selectedIndex property to determine which item is currently selected.

You can populate a ListBox using an array of strings or you can use an array of objects, in which case the ListBox.displayMemberPath property determines which object property is displayed on the list.

To display items that contain HTML rather than plain text, set the ListBox.isContentHtml property to true.

The ListBox control supports the following keyboard commands:

Key CombinationAction
Up/DownSelect the previous/next item
PageUp/DownSelect the item one page above or below the selection
Home/EndSelect the first/last items
SpaceToggle the checkbox in the current item (see the checkedMemberPath property)
Other charactersSearch for items that contain the text typed (multi-character auto-search)

The example below creates a ListBox control and populates it using a 'countries' array. The control updates its ListBox.selectedIndex and ListBox.selectedItem properties as the user moves the selection.

Example

Type parameters

Heirarchy

Constructors

Properties

Methods

Events

Constructors

constructor

  • new ListBox(element: any, options?: any): ListBox

  • Initializes a new instance of the ListBox class.

    Parameters

    • element: any

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

    • Optional options: any

      The JavaScript object containing initialization data for the control.

    Returns ListBox

Properties

ariaLabelledBy

ariaLabelledBy: string

Gets or sets the aria-labelledby attribute of ListBox input element.

caseSensitiveSearch

caseSensitiveSearch: boolean

Gets or sets a value that determines whether searches performed while the user types should case-sensitive.

The default value for this property is false.

checkedItems

checkedItems: any[]

Gets or sets an array containing the items that are currently checked.

Setting this property does not change the value of the selectedIndex property.

checkedMemberPath

checkedMemberPath: string

Gets or sets the name of the property used to control check boxes placed next to each item.

Use this property to create multi-select ListBoxes.

When an item is checked or unchecked, the control raises the itemChecked event.

Use the selectedItem property to retrieve the item that was checked or unchecked, or use the checkedItems property to retrieve the list of items that are currently checked.

The default value for this property is the empty string ''.

collectionView

collectionView: ICollectionView<T>

Gets the ICollectionView object used as the item source.

displayMemberPath

displayMemberPath: string

Gets or sets the name of the property to use as the visual representation of the items.

The default value for this property is the empty string ''.

hostElement

hostElement: HTMLElement

Gets the DOM element that is hosting the control.

isContentHtml

isContentHtml: boolean

Gets or sets a value indicating whether items contain plain text or HTML.

The default value for this property is false.

isDisabled

isDisabled: boolean

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

Disabled controls cannot get mouse or keyboard events.

isTouching

isTouching: boolean

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

isUpdating

isUpdating: boolean

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

itemFormatter

itemFormatter: IItemFormatter

Gets or sets a function used to customize the values shown on the list.

The function takes two arguments, the item index and the default text or html, and returns the new text or html to display.

If the formatting function needs a scope (i.e. a meaningful 'this' value), then remember to set the filter using the 'bind' function to specify the 'this' object. For example:

listBox.itemFormatter = customItemFormatter.bind(this);
function customItemFormatter(index, content) {
    if (this.makeItemBold(index)) {
        content = '&lt;b&gt;' + content + '&lt;/b&gt;';
    }
    return content;
}

itemRole

itemRole: string

Gets or sets the value or the "role" attribute added to the list items.

The default value for this property is the string "option".

itemsSource

itemsSource: any

Gets or sets the array or ICollectionView object that contains the list items.

maxHeight

maxHeight: number

Gets or sets the maximum height of the list (in pixels).

The default value for this property is null, which means the ListBox has no maximum height limit.

rightToLeft

rightToLeft: boolean

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

selectedIndex

selectedIndex: number

Gets or sets the index of the currently selected item.

selectedItem

selectedItem: any

Gets or sets the item that is currently selected.

selectedValue

selectedValue: any

Gets or sets the value of the selectedItem obtained using the selectedValuePath.

selectedValuePath

selectedValuePath: string

Gets or sets the name of the property used to get the selectedValue from the selectedItem.

The default value for this property is the empty string ''.

showGroups

showGroups: boolean

Gets or sets a value that determines whether the ListBox should include group header items to delimit data groups.

Data groups are created by modifying the ICollectionView.groupDescriptions property of the ICollectionView object used as an itemsSource.

The ListBox only shows the first level of grouping.

The default value for this property is false.

tabOrder

tabOrder: number

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.

virtualizationThreshold

virtualizationThreshold: number

Gets or sets the minimum number of rows and/or columns required to enable virtualization.

When the ListBox is virtualized, only the items that are currently visible are added to the DOM. This makes a huge difference in performance when the ListBox contains a large number of items (say 1,000 or so).

The default value for this property is a very big number, meaning virtualization is disabled. To enable virtualization, set its value to 0 or a positive number.

Virtualization assumes a vertically stacked layout, so it is automatically disabled if the ListBox uses a multi-column display (such as a flexbox or grid layout).

Methods

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.

    • Optional capture: boolean

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

    • Optional passive: boolean

      Indicates that the handler will never call preventDefault().

    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');

    @param classNames Names of classes to add to the control's host element. @param template An HTML string that defines the control template. @param parts A dictionary of part variables and their names. @param namePart Name of the part to be named after the host element. This determines how the control submits data when used in forms.

    Parameters

    • classNames: string
    • template: string
    • parts: Object
    • Optional namePart: string

    Returns HTMLElement

beginUpdate

  • beginUpdate(): void

containsFocus

  • containsFocus(): boolean

  • Checks whether this control contains the focused element.

    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

    • fn: Function

      Function to be executed.

    Returns void

dispose

  • dispose(): void

  • Disposes of the control and all its resources.

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

    Returns void

endUpdate

  • endUpdate(shouldInvalidate?: boolean): void

  • Resumes notifications suspended by calls to beginUpdate.

    Parameters

    • Optional shouldInvalidate: boolean

      should invalidate the control. Default value for this parameter is true.

    Returns void

focus

  • focus(): void

  • Sets the focus to this control.

    Returns void

getDisplayText

  • getDisplayText(index: number): string

  • Gets the text displayed for the item at a given index (as plain text).

    Parameters

    • index: number

      The index of the item in the itemsSource.

    Returns string

getDisplayValue

  • getDisplayValue(index: number, ignoreItemFormatter?: boolean): string

  • Gets the string displayed for the item at a given index.

    The string may be plain text or HTML, depending on the setting of the isContentHtml property.

    Parameters

    • index: number

      The index of the item in the itemsSource.

    • Optional ignoreItemFormatter: boolean

    Returns string

getItemChecked

  • getItemChecked(index: number): boolean

  • Gets the checked state of an item on the list.

    This method can be used with multi-select ListBoxes (see the checkedMemberPath property).

    Parameters

    • index: number

      Item index.

    Returns boolean

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).

    Returns string

hasOwnProperty

  • hasOwnProperty(v: PropertyKey): boolean

  • Determines whether an object has a property with the specified name.

    Parameters

    • v: PropertyKey

      A property name.

    Returns boolean

indexOf

  • indexOf(e: HTMLElement): number

  • Gets the data index of an element within the list.

    Parameters

    • e: HTMLElement

      Element to search for.

    Returns number

    The index of the element in the list, or -1 if the element is not a member of the list.

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.

    Returns void

invalidate

  • invalidate(fullUpdate?: boolean): void

  • Invalidates the control causing an asynchronous refresh.

    Parameters

    • Optional fullUpdate: boolean

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

    Returns void

isItemEnabled

  • isItemEnabled(index: number): boolean

  • Gets a value that determines whether the item at a given index is enabled.

    Parameters

    • index: number

      The index of the item in the itemsSource.

    Returns boolean

isPrototypeOf

  • isPrototypeOf(v: Object): boolean

  • Determines whether an object exists in another object's prototype chain.

    Parameters

    • v: Object

      Another object whose prototype chain is to be checked.

    Returns boolean

loadList

  • loadList(): void

  • Loads the list with items from the current itemsSource.

    Returns void

onCheckedItemsChanged

onFormatItem

onGotFocus

onInvalidInput

onItemChecked

onItemsChanged

onLoadedItems

onLoadingItems

onLostFocus

onRefreshed

onRefreshing

onSelectedIndexChanged

  • onSelectedIndexChanged(e?: EventArgs): void

propertyIsEnumerable

  • propertyIsEnumerable(v: PropertyKey): boolean

  • Determines whether a specified property is enumerable.

    Parameters

    • v: PropertyKey

      A property name.

    Returns boolean

refresh

  • refresh(fullUpdate?: boolean): void

  • Refreshes the control.

    Parameters

    • Optional fullUpdate: boolean

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

    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

    • Optional target: EventTarget

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

    • Optional type: string

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

    • Optional fn: any

      Handler to remove. If null, removes all handlers.

    • Optional capture: boolean

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

    Returns number

    The number of listeners removed.

setItemChecked

  • setItemChecked(index: number, checked: boolean | null): void

  • Sets the checked state of an item on the list.

    This method is applicable only on multi-select ListBoxes (see the checkedMemberPath property).

    If the checked state of the item changes, the item becomes selected.

    Parameters

    • index: number

      Item index.

    • checked: boolean | null

      Item's new checked state.

    Returns void

showSelection

  • showSelection(setFocus?: boolean): void

  • Highlights the selected item and scrolls it into view.

    Parameters

    • Optional setFocus: boolean

      Whether to set the focus to the list after scrolling the selected item into view.

    Returns void

toLocaleString

  • toLocaleString(): string

  • Returns a date converted to a string using the current locale.

    Returns string

toString

  • toString(): string

  • Returns a string representation of an object.

    Returns string

toggleItemChecked

  • toggleItemChecked(index: number): void

  • Toggles the checked state of an item on the list. This method is applicable only to multi-select ListBoxes (see the checkedMemberPath property).

    Parameters

    • index: number

      Item index.

    Returns void

valueOf

  • valueOf(): Object

  • Returns the primitive value of the specified object.

    Returns Object

Static disposeAll

  • disposeAll(e?: HTMLElement): void

  • Disposes of all Wijmo controls contained in an HTML element.

    Parameters

    • Optional e: HTMLElement

      Container element.

    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').

    Returns Control

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 Control.invalidateAll method so the contained Wijmo controls will update their layout information properly.

    Parameters

    • Optional e: HTMLElement

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

    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

    • Optional e: HTMLElement

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

    Returns void

Events

checkedItemsChanged

checkedItemsChanged: Event<ListBox<any>, EventArgs>

Occurs when the value of the checkedItems property changes.

formatItem

formatItem: Event<ListBox<any>, FormatItemEventArgs>

Occurs when an element representing a list item has been created.

This event can be used to format list items for display. It is similar in purpose to the itemFormatter property, but has the advantage of allowing multiple independent handlers.

The FormatItemEventArgs object passed as a parameter has a data property that refers to the data item bound to the item and an index property that provides the item index into the current view.

If the showGroups property is set to true and the item represents a group header, then the data property contains a reference to a CollectionViewGroup object represents the group. This object contains the group's name, items, and groupDescription. Since group headers do not correspond to actual data items, the index property in this case is set to -1.

gotFocus

gotFocus: Event<Control, EventArgs>

Occurs when the control gets the focus.

invalidInput

invalidInput: Event<Control, CancelEventArgs>

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.

itemChecked

itemChecked: Event<ListBox<any>, EventArgs>

Occurs when the current item is checked or unchecked by the user.

This event is raised when the checkedMemberPath is set to the name of a property to add check boxes to each item in the control.

Use the selectedItem property to retrieve the item that was checked or unchecked.

itemsChanged

itemsChanged: Event<ListBox<any>, EventArgs>

Occurs when the list of items changes.

loadedItems

loadedItems: Event<ListBox<any>, EventArgs>

Occurs after the list items have been generated.

loadingItems

loadingItems: Event<ListBox<any>, EventArgs>

Occurs before the list items are generated.

lostFocus

lostFocus: Event<Control, EventArgs>

Occurs when the control loses the focus.

refreshed

refreshed: Event<Control, EventArgs>

Occurs after the control has refreshed its contents.

refreshing

refreshing: Event<Control, EventArgs>

Occurs when the control is about to refresh its contents.

selectedIndexChanged

selectedIndexChanged: Event<ListBox<any>, EventArgs>

Occurs when the value of the selectedIndex property changes.