The MultiSelect control allows users to select multiple items from drop-down lists that contain custom objects or simple strings.
The MultiSelect control extends ComboBox, with all the usual properties, including itemsSource and displayMemberPath.
Like the ListBox control, it has a checkedMemberPath property that defines the name of the property that determines whether an item is checked or not.
The items currently checked (selected) can be obtained using the checkedItems property.
The control header is fully customizable. By default, it shows up to two items selected and the item count after that. You can change the maximum number of items to display (maxHeaderItems), the message shown when no items are selected (placeholder), and the format string used to show the item count (headerFormat).
Alternatively, you can provide a function to generate the header content based on whatever criteria your application requires (headerFormatter).
The example below shows how you can use a MultiSelect control to select multiple items from a drop-down list:
{@sample Input/MultiSelect/Overview Example}
constructor(element: any, options?: any): MultiSelect
Initializes a new instance of the MultiSelect 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 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**.
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.
Gets or sets the name of the property used to control the checkboxes placed next to each item.
Gets or sets a value that determines whether the MultiSelectListBox in the drop-down should automatically select all the filtered items when the filter text changes.
The default value for this property is **true**.
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 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 Toggle by default.
Gets the ICollectionView object used as the item source.
Gets or sets the template used to instantiate DropDown controls.
Gets or sets the delay, in milliseconds, between when a keystroke occurs and when the search is performed to update the filter.
This property is relevant only when the showFilterInput property is set to **true**.
The default value for this property is **500** milliseconds.
Gets or sets the name of the property to use as the visual representation of the items.
Gets the drop down element shown when the isDroppedDown property is set to true.
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.
Gets or sets the string used as a placeholder for the filter input element on the MultiSelectListBox drop-down.
The default value for this property is **null**, which causes the control to use a localized version of the string "Filter".
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.
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**.
Gets or sets the format string used to create the header content when the control has more than maxHeaderItems items checked.
The format string may contain the '{count}' replacement string which gets replaced with the number of items currently checked.
The default value for this property is **null**, which causes the control to use a localized version of the string "{count:n0} items selected".
Gets or sets a function that gets the text displayed in the control header.
By default, the control header content is determined based on the placeholder, maxHeaderItems, and on the current selection.
You may customize the header content by specifying a function that returns a custom string based on whatever criteria your application requires.
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.
Gets the DOM element that is hosting the control.
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.
Gets or sets the "type" attribute of the HTML input element hosted by the control.
The default value for this property is **'text'**.
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**.
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**.
Gets or sets a value that determines whether the control is disabled.
Disabled controls cannot get mouse or keyboard events.
Gets or sets a value that indicates whether the drop down is currently visible.
The default value for this property is **false**.
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.
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**.
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.
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 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 = '<b>' + content + '</b>';
}
return content;
}
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 collectionView property.
The ComboBox selection is determined by the current item in its 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 collectionView to null.
Gets or sets the maximum height of the drop-down list, in pixels.
The default value for this property is **200** pixels.
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.
Gets or sets the maximum number of items to display on the control header.
If no items are selected, the header displays the text specified by the placeholder property.
If the number of selected items is smaller than or equal to the value of the maxHeaderItems property, the selected items are shown in the header.
If the number of selected items is greater than maxHeaderItems, the header displays the selected item count instead.
The default value for this property is **2**.
Gets or sets the string shown as a hint when the control is empty.
Gets a value indicating whether the control is hosted in an element with right-to-left layout.
Gets or sets the string to be used as a label for the "Select All" checkbox that is displayed when the showSelectAllCheckbox property is set to true.
The default value for this property is **null**, which causes the control to use a localized version of the string "Select All".
Gets or sets the index of the currently selected item in the drop-down list.
Gets or sets the item that is currently selected in the drop-down list.
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.
Gets or sets the name of the property used to get the selectedValue from the selectedItem.
Gets or sets a value that indicates whether the control should display a drop-down button.
The default value for this property is **true**.
Gets or sets whether the control should display a "filter" input above the items to filter the items displayed.
The default value for this property is **false**.
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 groupDescriptions property of the ICollectionView object used as an itemsSource.
The default value for this property is **false**.
Gets or sets whether the control should display a "Select All" checkbox above the items to select or de-select all items.
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 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:
```css .wj-listbox-item { white-space: pre; } ```
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.virtializationThreshold property.
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, trimText?: this): string
Gets the string displayed in the input element for the item at a given index (always plain text).
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(search: string, fullMatch: boolean, dry?: boolean): number
Gets the index of the first item that matches a given string.
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.
onCheckedItemsChanged(e?: EventArgs): void
Raises the checkedItemsChanged event.
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.
onIsDroppedDownChanged(e?: EventArgs): void
Raises the isDroppedDownChanged event.
onIsDroppedDownChanging(e: CancelEventArgs): boolean
Raises the isDroppedDownChanging event.
onItemsSourceChanged(e?: EventArgs): void
Raises the itemsSourceChanged 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.
onTextChanged(e?: EventArgs): void
Raises the textChanged 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.
selectAll(): void
Sets the focus to the control and selects all its content.
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 after the drop down is shown or hidden.
Occurs before the drop down is shown or hidden.
Occurs when the value of the itemsSource property changes.
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.