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ComboBox Class

ComboBox Class

The ComboBox control allows users to pick strings from lists.

The control automatically completes entries as the user types, and allows users to show a drop-down list with the items available.

Use the ComboBox.itemsSource property to populate the list of options. The items may be strings or objects. If the items are objects, use the ComboBox.displayMemberPath to define which property of the items will be displayed in the list and use the ComboBox.selectedValuePath property to define which property of the items will be used to set the combo's ComboBox.selectedValue property.

Use the ComboBox.selectedIndex or the ComboBox.text properties to determine which item is currently selected.

The ComboBox.isRequired property determines whether the control must have a non-null value or whether it can be set to null (by deleting the content of the control). If the value is set to null, the ComboBox.selectedIndex is set to -1.

The ComboBox.isEditable property determines whether users can enter values that are not present in the list.

The example below creates a ComboBox control and populates it with a list of countries. The ComboBox searches for the country as the user types. The ComboBox.isEditable property is set to false, so the user must select one of the items in the list.

Example

Type parameters

  • T

Heirarchy

Constructors

Properties

Methods

Events

Constructors

constructor

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

  • Initializes a new instance of the ComboBox class.

    Parameters

    • element: any

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

    • Optional options: any

      The JavaScript object containing initialization data for the control.

    Returns ComboBox

Properties

autoExpandSelection

autoExpandSelection: boolean

Gets or sets a value that indicates whether the control should automatically expand the selection to whole words/numbers when the control is clicked.

The default value for this property is true.

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.

clickAction

clickAction: ClickAction

Gets or sets a value that specifies the action to perform when the user clicks the input element in the control.

For most drop-down controls, this property is set to ClickAction.Select by default. This setting allows users to select portions of the text with the mouse.

For drop-down controls that display non-editable text (such as the MultiSelect), this property is set to ClickAction.Toggle by default.

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.

dropDown

dropDown: HTMLElement

Gets the drop down element shown when the isDroppedDown property is set to true.

dropDownCssClass

dropDownCssClass: string

Gets or sets a CSS class name to add to the control's drop-down element.

This property is useful when styling the drop-down element, because it is shown as a child of the document body rather than as a child of the control itself, which prevents using CSS selectors based on the parent control.

handleWheel

handleWheel: boolean

Gets or sets a value that determines whether the user can use the mouse wheel to change the currently selected item.

The default value for this property is true.

headerPath

headerPath: string | null

Gets or sets the name of a property to use for getting the value displayed in the control's input element.

The default value for this property is null, which causes the control to display the same content in the input element as in the selected item of the drop-down list.

Use this property if you want to decouple the value shown in the input element from the values shown in the drop-down list. For example, the input element could show an item's name and the drop-down list could show additional detail.

hostElement

hostElement: HTMLElement

Gets the DOM element that is hosting the control.

inputElement

inputElement: HTMLInputElement

Gets the HTML input element hosted by the control.

Use this property in situations where you want to customize the attributes of the input element.

inputType

inputType: string

Gets or sets the "type" attribute of the HTML input element hosted by the control.

The default value for this property is 'text'.

isAnimated

isAnimated: boolean

Gets or sets a value that indicates whether the control should use a fade-in animation when displaying the drop-down.

The default value for this property is false.

isContentHtml

isContentHtml: boolean

Gets or sets a value indicating whether the drop-down list displays items as plain text or as 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.

isDroppedDown

isDroppedDown: boolean

Gets or sets a value that indicates whether the drop down is currently visible.

The default value for this property is false.

isEditable

isEditable: boolean

Gets or sets a value that determines whether the content of the input element should be restricted to items in the itemsSource collection.

The default value for this property is false on the ComboBox control, and true on the AutoComplete and InputTime controls.

isReadOnly

isReadOnly: boolean

Gets or sets a value that indicates whether the user can modify the control value using the mouse and keyboard.

The default value for this property is false.

isRequired

isRequired: boolean

Gets or sets a value that determines whether the control value must be set to a non-null value or whether it can be set to null (by deleting the content of the control).

This property defaults to true for most controls, including ComboBox, InputDate, InputTime, InputDateTime, and InputColor. It defaults to false for the AutoComplete control.

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 in the drop-down 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:

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

itemsSource

itemsSource: any

Gets or sets the array or ICollectionView object that contains the items to select from.

Setting this property to an array causes the ComboBox to create an internal ICollectionView object that is exposed by the ComboBox.collectionView property.

The ComboBox selection is determined by the current item in its ComboBox.collectionView. By default, this is the first item in the collection. You may change this behavior by setting the wijmo.CollectionView.currentItem property of the ComboBox.collectionView to null.

listBox

listBox: ListBox

Gets the ListBox control shown in the drop-down.

maxDropDownHeight

maxDropDownHeight: number

Gets or sets the maximum height of the drop-down list, in pixels.

The default value for this property is 200 pixels.

maxDropDownWidth

maxDropDownWidth: number

Gets or sets the maximum width of the drop-down list.

The width of the drop-down list is also limited by the width of the control itself (that value represents the drop-down's minimum width).

The default value for this property is null, which means the drop-down has no maximum width limit.

placeholder

placeholder: string

Gets or sets the string shown as a hint when the control is empty.

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 in the drop-down list.

selectedItem

selectedItem: any

Gets or sets the item that is currently selected in the drop-down list.

selectedValue

selectedValue: any

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

If the selectedValuePath property is not set, gets or sets the value of the control's selectedItem property.

If the itemsSource property is not set, gets or sets the value of the control's text property.

selectedValuePath

selectedValuePath: string

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

showDropDownButton

showDropDownButton: boolean

Gets or sets a value that indicates whether the control should display a drop-down button.

The default value for this property is true.

showGroups

showGroups: boolean

Gets or sets a value that determines whether the drop-down 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 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.

text

text: string | null

Gets or sets the text shown on the control.

trimText

trimText: boolean

Gets or sets a value that determines whether values in the control's input element should be trimmed by removing leading and trailing spaces.

The default value for this property is true.

To see leading and trailing spaces in the drop-down list items, you may have to apply a CSS rule such as this one:

.wj-listbox-item {
    white-space: pre;
}

virtualizationThreshold

virtualizationThreshold: number

Gets or sets the minimum number of rows and/or columns required to enable virtualization in the drop-down ListBox.

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.

For more detals, please see the ListBox.virtualizationThreshold property.

Static controlTemplate

controlTemplate: string

Gets or sets the template used to instantiate DropDown controls.

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

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, trimText?: boolean): string

  • Gets the string displayed in the input element for the item at a given index (always plain text).

    Parameters

    • Optional index: number

      The index of the item to retrieve the text for.

    • Optional trimText: boolean

      Optionally override the value of the trimText property.

    Returns string

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(search: string, fullMatch: boolean, dry?: boolean): number

  • Gets the index of the first item that matches a given string.

    Parameters

    • search: string

      String to search for.

    • fullMatch: boolean

      Whether to look for a full match or just the start of the string.

    • Optional dry: boolean

    Returns number

    The index of the item, or -1 if not found.

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

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

onInvalidInput

onItemsSourceChanged

onRefreshed

onRefreshing

onSelectedIndexChanged

  • onSelectedIndexChanged(e?: EventArgs): void

onTextChanged

propertyIsEnumerable

  • propertyIsEnumerable(v: PropertyKey): boolean

  • Determines whether a specified property is enumerable.

    Parameters

    • v: PropertyKey

      A property name.

    Returns boolean

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.

selectAll

  • selectAll(): void

  • Sets the focus to the control and selects all its content.

    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

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

formatItem

formatItem: Event<ListBox, FormatItemEventArgs>

Event that fires when items in the drop-down list are created.

You can use this event to modify the HTML in the list items. For details, see the ListBox.formatItem event.

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.

isDroppedDownChanged

isDroppedDownChanged: Event<DropDown, EventArgs>

Occurs after the drop down is shown or hidden.

isDroppedDownChanging

isDroppedDownChanging: Event<DropDown, CancelEventArgs>

Occurs before the drop down is shown or hidden.

itemsSourceChanged

itemsSourceChanged: Event<ComboBox<any>, EventArgs>

Occurs when the value of the itemsSource property changes.

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<ComboBox<any>, EventArgs>

Occurs when the value of the selectedIndex property changes.

textChanged

textChanged: Event<DropDown, EventArgs>

Occurs when the value of the text property changes.