ListComboBox

A combo box whose popup presents a list of choices
Pet:
Canary
Cat
Chicken
Chinchilla
Cockatiel
Cricket
Dog
Ferret
Finch
Fish
Frog
Gerbil
Guinea Pig
Hamster
Hermit Crab
Lizard
Mouse
Parakeet
Parrot
Pig
Rabbit
Rat
Snail
Snake
Spider
Turtle
Demo: AutoCompleteComboBox selects choices as you type
Fruit:
Acai
Akee
Apple
Apricot
Avocado
Banana
Bilberry
Black sapote
Blackberry
Blackcurrant
Blood orange
Blueberry
Boysenberry
Cantaloupe
Cherimoya
Cherry
Chico fruit
Clementine
Cloudberry
Coconut
Crab apple
Cranberry
Cucumber
Currant
Damson
Date
Dragonfruit
Durian
Elderberry
Feijoa
Fig
Goji berry
Gooseberry
Grape
Grapefruit
Guava
Honeyberry
Honeydew
Horned melon
Huckleberry
Jabuticaba
Jackfruit
Jambul
Japanese plum
Jostaberry
Jujube
Juniper berry
Kiwifruit
Kumquat
Lemon
Lime
Longan
Loquat
Lychee
Mandarin
Mango
Mangosteen
Marionberry
Miracle fruit
Mulberry
Nance
Nectarine
Orange
Papaya
Passionfruit
Peach
Pear
Persimmon
Pineapple
Pineberry
Plantain
Plum
Pluot
Pomegranate
Pomelo
Purple mangosteen
Quince
Rambutan
Raspberry
Redcurrant
Salak
Salal berry
Salmonberry
Satsuma
Soursop
Star apple
Star fruit
Strawberry
Surinam cherry
Tamarillo
Tamarind
Tangerine
Ugli fruit
Watermelon
White currant
White sapote
Yuzu
Demo: FilterComboBox also filters down the set of choices as you type

Overview

A ListComboBox is a common type of ComboBox in which the associated popup contains a list of choices. The specific type of input and list can be varied. ListComboBox can be used directly, although it's also the starting point for more specific types of combo boxes:

AutoCompleteComboBox pairs an AutoCompleteInput in the input role with a standard ListBox in the list role. This gives the user in-line auto-completion against the same set of choices shown in the list.

The FilterComboBox variation gives the list role to FilterListBox. Accordingly, as the user types, they can narrow down the set of available choices.

Usage

import ListComboBox from 'elix/define/ListComboBox.js';
const listComboBox = new ListComboBox(); // or
const listComboBox = document.createElement('elix-list-combo-box');

In HTML:

<script type="module" src="node_modules/elix/define/ListComboBox.js"></script>
<elix-list-combo-box aria-label="Pet">
  <div>Cat</div>
  <div>Dog</div>
  <div>Fish</div>
</elix-list-combo-box>

Use ListComboBox when:

  • You want to offer the user a list of common responses, but also want to allow them to enter their own response. If you want to force the user to choose from a fixed list, consider DropdownList.
  • The list of common responses is potentially large. It will usually be easier for the user to type the beginning of a response in a ListComboBox than to select the item from a long list in a DropdownList, for example. For especially large lists, FilterComboBox makes it easier for users to search.
  • Space is limited, or the setting controlled by the combo box is not particularly high priority. In other situations, a simpler ListBox may be preferred.

See also

API

Class hierarchy:

The element defines the following shadow parts:

  • backdrop: default type is Hidden
  • down-icon: the icon shown in the toggle if the popup will open or close in the down direction
  • input: the text input element, default type is input element
  • list: the list of choices, default type is ListBox
  • popup: the popup element, default type is Popup
  • popup-toggle: the element that lets the user know they can open the popup, default type is UpDownToggle
  • source: the element used as the reference point for positioning the popup, generally the element that invokes the popup, default type is div element
  • up-icon: the icon shown in the toggle if the popup will open or close in the up direction

canSelectNext property

True if the selection can be moved to the next item, false if not (the selected item is the last item in the list).

Type: boolean

Defined by SingleSelectionMixin

canSelectPrevious property

True if the selection can be moved to the previous item, false if not (the selected item is the first one in the list).

Type: boolean

Defined by SingleSelectionMixin

close(closeResult) method

Close the component (if not already closed).

Some components like AlertDialog want to indicate why or how they were closed. To support such scenarios, you can supply a value to the optional closeResult parameter. This closeResult will be made available in the whenClosed promise and the state.closeResult member.

Parameters:

  • closeResult: objectan indication of how or why the element closed

Defined by OpenCloseMixin

closed property

True if the element is currently closed.

This read-only property is provided as a convenient inverse of opened.

Type: boolean

Defined by OpenCloseMixin

closed event

Raised when the component closes.

Defined by OpenCloseMixin

closeFinished property

True if the element has completely closed.

For components not using asynchronous open/close effects, this property returns the same value as the closed property. For elements that have a true value of state.openCloseEffects (e.g., elements using TransitionEffectMixin), this property returns true only if state.effect is "close" and state.effectPhase is "after".

Type: boolean

Defined by OpenCloseMixin

disabled property

True if the component is disabled, false (the default) if not.

The value of this property will be reflected to the disabled attribute so that it can be referenced in CSS. Note that this non-native implementation of the disabled attribute will not trigger the :disabled CSS pseudo-class, so your style rules will have to reference the presence or absence of the disabled attribute. That is, instead of writing

my-component:disabled { ... }

write this instead

my-component[disabled] { ... }

Like the native disabled attribute, this attribute is boolean. That means that it's existence in markup sets the attribute, even if set to an empty string or a string like "false".

Type: boolean

Default: false

Defined by DisabledMixin

form property

The ID of the form element with which this element is associated, or null if the element is not associated with any form. This is provided for consistency with the native HTML form property.

Type: string

Defined by FormElementMixin

horizontalAlign property

The alignment of the popup with respect to the source button.

  • start: popup and source are aligned on the leading edge according to the text direction
  • end: popup and source are aligned on the trailing edge according to the text direction
  • left: popup and source are left-aligned
  • right: popup and source are right-aligned
  • `stretch: both left and right edges are aligned
     <p><span class="apiLabel">Type:</span> <code>'start'|'end'|'left'|'right'|'stretch'</code></p> <p><span class="apiLabel">Default:</span> <code>'start'</code></p>  <p> Defined by <a href="PopupSource">PopupSource</a> </p> 

input property

The combo box's input element.

Type: Element|null

Defined by ComboBox

inputPartType property

The class or tag used to create the input part into which the user can enter text.

Type: (component class constructor)|HTMLTemplateElement|string

Default: 'input'

Defined by ComboBox

[internal.defaultState] property

The default state for the component. This can be extended by mixins and classes to provide additional default state.

Type: PlainObject

Defined by ReactiveMixin

[internal.delegatesFocus] property

Returns true if the component is delegating its focus.

A component using DelegateFocusMixin will always have this property be true unless a class takes measures to override it.

Type: boolean

Default: true

Defined by DelegateFocusMixin

[internal.goDown]() method

Invokes selectNext to select the next item.

Defined by DirectionSelectionMixin

[internal.goEnd]() method

Invokes selectLast to select the next item.

Defined by DirectionSelectionMixin

[internal.goLeft]() method

Invokes selectPrevious to select the previous item.

If the element has a rightToLeft property and it is true, then this selects the next item.

Defined by DirectionSelectionMixin

[internal.goNext]() method

Invokes selectNext to select the next item.

Defined by DirectionSelectionMixin

[internal.goPrevious]() method

Invokes selectPrevious to select the previous item.

Defined by DirectionSelectionMixin

[internal.goRight]() method

Invokes selectNext to select the next item.

If the element has a rightToLeft property and it is true, then this selects the previous item.

Defined by DirectionSelectionMixin

[internal.goStart]() method

Invokes selectFirst to select the first item.

Defined by DirectionSelectionMixin

[internal.goUp]() method

Invokes selectPrevious to select the previous item.

Defined by DirectionSelectionMixin

[internal.ids] property

A convenient shortcut for looking up an element by ID in the component's Shadow DOM subtree.

Example: if component's template contains a shadow element <button id="foo">, you can use the reference this[internal.ids].foo to obtain the corresponding button in the component instance's shadow tree. The ids property is simply a shorthand for getElementById, so this[internal.ids].foo is the same as this[internal.shadowRoot].getElementById('foo').

Type: object

Defined by ShadowTemplateMixin

[internal.keydown]() method

See the symbols documentation for details.

Defined by KeyboardMixin

[internal.render](changed) method

Render the indicated changes in state to the DOM.

The default implementation of this method does nothing. Override this method in your component to update your component's host element and any shadow elements to reflect the component's new state. See the rendering example.

Be sure to call super in your method implementation so that your component's base classes and mixins have a chance to perform their own render work.

Parameters:

  • changed: ChangedFlagsdictionary of flags indicating which state members have changed since the last render

Defined by ReactiveMixin

[internal.renderChanges]() method

Render any pending component changes to the DOM.

This method does nothing if the state has not changed since the last render call.

ReactiveMixin will invoke this method following a setState call; you should not need to invoke this method yourself.

This method invokes the internal render method, then invokes the rendered method.

Defined by ReactiveMixin

[internal.rendered](changed) method

Perform any work that must happen after state changes have been rendered to the DOM.

The default implementation of this method does nothing. Override this method in your component to perform work that requires the component to be fully rendered, such as setting focus on a shadow element or inspecting the computed style of an element. If such work should result in a change in component state, you can safely call setState during the rendered method.

Be sure to call super in your method implementation so that your component's base classes and mixins have a chance to perform their own post-render work.

Parameters:

  • changed: ChangedFlags

Defined by ReactiveMixin

[internal.setState](changes) method

Update the component's state by merging the specified changes on top of the existing state. If the component is connected to the document, and the new state has changed, this returns a promise to asynchronously render the component. Otherwise, this returns a resolved promise.

Parameters:

  • changes: PlainObjectthe changes to apply to the element's state

Returns: Promise - resolves when the new state has been rendered

Defined by ReactiveMixin

[internal.state] property

The component's current state.

The returned state object is immutable. To update it, invoke internal.setState.

It's extremely useful to be able to inspect component state while debugging. If you append ?elixdebug=true to a page's URL, then ReactiveMixin will conditionally expose a public state property that returns the component's state. You can then access the state in your browser's debug console.

Type: PlainObject

Defined by ReactiveMixin

[internal.stateEffects](state, changed) method

Ask the component whether a state with a set of recently-changed fields implies that additional second-order changes should be applied to that state to make it consistent.

This method is invoked during a call to internal.setState to give all of a component's mixins and classes a chance to respond to changes in state. If one mixin/class updates state that it controls, another mixin/class may want to respond by updating some other state member that it controls.

This method should return a dictionary of changes that should be applied to the state. If the dictionary object is not empty, the internal.setState will apply the changes to the state, and invoke this stateEffects method again to determine whether there are any third-order effects that should be applied. This process repeats until all mixins/classes report that they have no additional changes to make.

See an example of how ReactiveMixin invokes the stateEffects to ensure state consistency.

Parameters:

  • state: PlainObjecta proposal for a new state
  • changed: ChangedFlagsthe set of fields changed in this latest proposal for the new state

Returns: PlainObject

Defined by ReactiveMixin

items property

The current set of items drawn from the element's current state.

Defined by DelegateItemsMixin

listPartType property

The class or tag used to create the list part - the list of available choices shown in the popup.

Type: (component class constructor)|HTMLTemplateElement|string

Default: ListBox

name property

The name of the form field that will be filled with this element's value. This is an analogue of the standard HTML name property.

Type: string

Defined by FormElementMixin

open() method

Open the element (if not already opened).

Defined by OpenCloseMixin

opened property

True if the element is currently opened.

This property can be set as a boolean attribute

Type: boolean|string

Defined by OpenCloseMixin

opened event

Raised when the component opens.

Defined by OpenCloseMixin

opened-changed event

Raised when the opened/closed state of the component changes.

Defined by OpenCloseMixin

placeholder property

The prompt text shown in the input if it is empty.

Type: string

Defined by ComboBox

popupPartType property

The class or tag used to create the popup part – the element responsible for displaying the popup and handling overlay behavior.

Type: (component class constructor)|HTMLTemplateElement|string

Default: Popup

Defined by PopupSource

popupPosition property

The preferred direction for the popup.

  • above: popup should appear above the source
  • below: popup should appear below the source
     <p><span class="apiLabel">Type:</span> <code>'above'|'below'</code></p> <p><span class="apiLabel">Default:</span> <code>'below'</code></p>  <p> Defined by <a href="PopupSource">PopupSource</a> </p> 

popupTogglePartType property

The class or tag used to create the popup-toggle part – the element that lets the user know they can open the popup.

Type: (component class constructor)|HTMLTemplateElement|string

Default: UpDownToggle

Defined by ComboBox

select() method

Selects all the text.

See the standard select documentation for details.

Defined by DelegateInputSelectionMixin

selected-index-changed event

Raised when the selectedIndex property changes.

Defined by SingleSelectionMixin

selectedIndex property

The index of the currently-selected item, or -1 if no item is selected.

Type: number

Defined by SingleSelectionMixin

selectedItem property

The currently-selected item, or null if no item is selected.

Type: Element

Defined by SingleSelectionMixin

selectFirst() method

Select the first item in the list.

Returns: Boolean True if the selection changed, false if not.

Defined by SingleSelectionMixin

selectionEnd property

The end index of the selected text.

See the standard input element documentation for details.

Defined by DelegateInputSelectionMixin

selectionRequired property

True if the list should always have a selection (if it has items).

Type: boolean

Default: false

Defined by SingleSelectionMixin

selectionStart property

The beginning index of the selected text.

See the standard input element documentation for details.

Defined by DelegateInputSelectionMixin

selectionWraps property

True if selection navigations wrap from last to first, and vice versa.

Type: boolean

Default: false

Defined by SingleSelectionMixin

selectLast() method

Select the last item in the list.

Returns: Boolean True if the selection changed, false if not.

Defined by SingleSelectionMixin

selectNext() method

Select the next item in the list.

If the list has no selection, the first item will be selected.

Returns: Boolean True if the selection changed, false if not.

Defined by SingleSelectionMixin

selectPrevious() method

Select the previous item in the list.

If the list has no selection, the last item will be selected.

Returns: Boolean True if the selection changed, false if not.

Defined by SingleSelectionMixin

setRangeText() method

Replaces a range of text.

See the standard setRangeText documentation for details.

Defined by DelegateInputSelectionMixin

setSelectionRange() method

Sets the start and end positions of the current text selection.

See the standard setSelectionRange documentation for details.

Defined by DelegateInputSelectionMixin

sourcePartType property

The class or tag used to create the source part - the button (or other element) the user can tap/click to invoke the popup.

Type: (component class constructor)|HTMLTemplateElement|string

Default: 'button'

Defined by PopupSource

toggle(opened) method

Toggle the open/close state of the element.

Parameters:

  • opened: booleantrue if the element should be opened, false if closed.

Defined by OpenCloseMixin

type property

The "type" of the form field, provided for consistency with the native HTML type property. The value of this property will be the same as the HTML tag name registered for the custom element.

Type: string

Defined by FormElementMixin

whenClosed() method

This method can be used as an alternative to listening to the "opened-changed" event, particularly in situations where you want to only handle the next time the component is closed.

Returns: Promise A promise that resolves when the element has completely closed, including the completion of any asynchronous opening effect.

Defined by OpenCloseMixin