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 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 displayMemberPath property determines which object property is displayed on the list.
To display items that contain HTML rather than plain text, set the isContentHtml property to true.
The ListBox control supports the following keyboard commands:
| Key Combination | Action |
|---|---|
| Up/Down | Select the previous/next item |
| PageUp/Down | Select the item one page above or below the selection |
| Home/End | Select the first/last items |
| Space | Toggle the checkbox in the current item (see the checkedMemberPath property) |
| Other characters | Search 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 selectedIndex and selectedItem properties as the user moves the selection.
{@sample Input/ListBox/Overview/purejs Example}
constructor(element: any, options?: any): ListBox
Initializes a new instance of the ListBox class.
The DOM element that hosts the control, or a CSS selector for the host element (e.g. '#theCtrl').
The JavaScript object containing initialization data for the control.
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**.
Gets or sets an array containing the items that are currently checked.
Setting this property does not change the value of the selectedIndex property.
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 **''**.
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 **''**.
Gets the DOM element that is hosting the control.
Gets or sets a value indicating whether items contain plain text or HTML.
The default value for this property is **false**.
Gets or sets a value that determines whether the control is disabled.
Disabled controls cannot get mouse or keyboard events.
Gets a value that indicates whether the control is currently handling a touch event.
Gets a value that indicates whether the control is currently being updated.
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 = '<b>' + content + '</b>';
}
return content;
}
Gets or sets the value or the "role" attribute added to the list items.
The default value for this property is the string **"option"**.
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.
Gets a value indicating whether the control is hosted in an element with right-to-left layout.
Gets or sets the item that is currently selected.
Gets or sets the value of the selectedItem obtained using the selectedValuePath.
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 **''**.
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 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**.
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.
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).
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.
Target element for the event.
String that specifies the event.
Function to execute when the event occurs.
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().
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');
```
Names of classes to add to the control's host element.
An HTML string that defines the control template.
A dictionary of part variables and their names.
Name of the part to be named after the host element. This determines how the control submits data when used in forms.
beginUpdate(): void
Suspends notifications until the next call to endUpdate.
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.
Function to be executed.
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.
disposeAll(e?: HTMLElement): void
Disposes of all Wijmo controls contained in an HTML element.
Container element.
endUpdate(): void
Resumes notifications suspended by calls to beginUpdate.
getControl(element: any): Control
Gets the control that is hosted in a given DOM element.
The DOM element that hosts the control, or a CSS selector for the host element (e.g. '#theCtrl').
getDisplayText(index: number): string
Gets the text displayed for the item at a given index (as plain text).
The index of the item in the itemsSource.
getDisplayValue(index: number): 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.
The index of the item in the itemsSource.
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).
Item index.
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).
indexOf(e: HTMLElement): number
Gets the data index of an element within the list.
Element to search for.
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.
Object that contains the initialization data.
invalidate(fullUpdate?: boolean): void
Invalidates the control causing an asynchronous refresh.
Whether to update the control layout as well as the content.
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.
Container element. If set to null, all Wijmo controls on the page will be invalidated.
isItemEnabled(index: number): void
Gets a value that determines whether the item at a given index is enabled.
The index of the item in the itemsSource.
onCheckedItemsChanged(e?: EventArgs): void
Raises the checkedItemsChanged event.
onFormatItem(e: FormatItemEventArgs): void
Raises the formatItem event.
FormatItemEventArgs that contains the event data.
onGotFocus(e?: EventArgs): void
Raises the gotFocus event.
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.
onItemChecked(e?: EventArgs): void
Raises the itemChecked event.
onItemsChanged(e?: EventArgs): void
Raises the itemsChanged event.
onLoadedItems(e?: EventArgs): void
Raises the loadedItems event.
onLoadingItems(e?: EventArgs): void
Raises the loadingItems event.
onLostFocus(e?: EventArgs): void
Raises the lostFocus event.
onRefreshed(e?: EventArgs): void
Raises the refreshed event.
onRefreshing(e?: EventArgs): void
Raises the refreshing event.
onSelectedIndexChanged(e?: EventArgs): void
Raises the selectedIndexChanged event.
refresh(fullUpdate?: boolean): void
Refreshes the control.
Whether to update the control layout as well as the content.
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.
Container element. If set to null, all Wijmo controls on the page will be invalidated.
removeEventListener(target?: EventTarget, type?: string, fn?: any, capture?: boolean): number
Removes one or more event listeners attached to elements owned by this Control.
Target element for the event. If null, removes listeners attached to all targets.
String that specifies the event. If null, removes listeners attached to all events.
Handler to remove. If null, removes all handlers.
Whether the listener is capturing. If null, removes capturing and non-capturing listeners.
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.
Item index.
Item's new checked state.
showSelection(setFocus?: this): void
Highlights the selected item and scrolls it into view.
Whether to set the focus to the list after scrolling the selected item into view.
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).
Item index.
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**.
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.
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.
Occurs after the control has refreshed its contents.
Occurs when the control is about to refresh its contents.
Occurs when the value of the selectedIndex property changes.