ARIA: combobox role

The combobox role identifies an element as an input that controls another element, such as a listbox or grid, that can dynamically pop up to help the user set the value of that input.

Description

A combobox is a composite widget that combines a named input field with a popup providing possible values for that input field. The purpose of a this widget is to improve user experience by helping the user select a value without having to type in the complete value and, optionally depending whether supported values are limited, preventing the user from entering invalid or otherwise unsupported values.

The combobox role is set on input that controls another element, such as a listbox or grid, that can dynamically pop up to help the user set the value of the input.

The combobox input field can either be a single-line text field that supports editing and typing, similar to a HTML <input> with a <datalist>, or an element that only displays the current value of the combobox.

A WAI-ARIA combobox only has one attribute that is required that authors specify: aria-expanded. However, it also has several other attributes which will be necessary to specify, depending on the combobox's implementation. These include aria-haspopup, aria-controls, aria-activedescendant, and aria-autocomplete.

Typically, the initial state of a combobox is collapsed, with aria-expanded="false" set. In the collapsed state, only the combobox element and, optionally a sibling button to invoke the popup, are visible. The aria-expanded, with the value set to false, is required when collapsed, because it indicates to assistive technologies that the widget is expandable.

The combobox is in the expanded state when both the combobox element showing its current value and its associated popup element are visible. When expanded, aria-expanded="true" must be set.

The popup element associated with a combobox can be either a listbox, tree, grid, or dialog element.

Comboboxes have an implicit aria-haspopup value of listbox, so including this attribute is optional if the popup is a listbox. If the combobox popup element is a tree, grid, or dialog (anything other than a listbox), the aria-haspopup attribute is required. The value of aria-haspopup must be either the tree, grid, dialog, or listbox role. Note that for this property, true means menu, so make sure that the value corresponds to the role of the popup, not a Boolean value.

When a combobox's popup is displayed, ensure the aria-controls attribute on the combobox element is set to the id of the popup listbox, tree, grid, or dialog element. This is how the relationship between the element with the combobox role and the popup it controls is indicated. (Note: In older ARIA specs, this was aria-owns rather than aria-controls, so you may see aria-owns in older combobox implementations. The aria-owns in the code should be updated to aria-controls!)

If the combobox UI includes a visible control, such as an icon, that allows the visibility of the popup to be controlled via pointer and touch events, that control should be a <button>, <input> of type button, or a button role element with a tabindex of -1. Doing so will allow the button to be focusable but not included in keyboard tab sequence. It must not be a descendant of the element with role combobox.

To be keyboard accessible, keyboard support for moving focus between the combobox input field element and elements contained in the popup listbox, tree, grid, or dialog, must be programmed in. One common convention is that Down Arrow moves focus from the input to the first focusable descendant of the popup element.

The aria-activedescendant property can be used to identify the currently active element of the combobox popup, for instance an option within a popup listbox, for implementations where DOM focus remains on the combobox. If DOM focus does not remain on the combobox when its popup is invoked, but rather DOM focus moves into the popup, such as a dialog, then aria-activedescendant may not be necessary.

If the combobox element is an <input> element, the value of the combobox is the input's value. Otherwise, the value of the combobox comes from its descendant elements.

If the combobox supports text input and provides autocompletion behavior, set aria-autocomplete on the combobox element to the value that corresponds to the provided behavior: inline, list, or both. The aria-autocomplete attribute indicates that inputting text will trigger display of one or more predictions of the user's intended value for the combobox and specifies how the predictions will be presented when made.

Every combobox must have an accessible name. If using an <input> element, the accessible name should come from the associated <label>. If not, if an appropriate label is visible in the content, provide the name via aria-labelledby. In other words, if there is an element in the user interface that serves as a label for the combobox input field, include aria-labelledby as an attribute on the element with the role of combobox, and set the value of the attribute to the id of the labelling element or elements. If no visible label is present, use aria-label instead. Not both.

Associated WAI-ARIA roles, states, and properties

aria-expanded

Required. Identifies whether the combobox is open (true) or closed (false).

aria-haspopup

Implied. If omitted, defaults to listbox. Also supports tree, grid, or dialog. Identifies the combobox has having a popout, and indicates the type.

Keyboard interactions

Down Arrow

Moves focus to the next option, or to the first option if none was selected.

Alt + Down Arrow (Optional)

If the popup is available but not displayed, displays the popup without moving focus.

Up Arrow

Moves focus to the previous option. Moving focus to the first option if focus was originally on the last option.

Alt + Up Arrow (Optional)

If the popup has focus, returns focus to the combobox, otherwise it closes the popup.

Enter

If the combobox is editable and an autocomplete suggestion is selected in the popup, accepts the suggestion either by placing the input cursor at the end of the accepted value in the combobox or by performing a default action on the value. For example, in a messaging application, the default action may be to add the accepted value to a list of message recipients and then clear the combobox so the user can add another recipient.

Examples

<label for="jokes">Pick what type of jokes you like</label>
<div class="combo-wrap">
  <input type="text" id="jokes" role="combobox" aria-controls="joketypes" aria-autocomplete="list" aria-expanded="false" data-active-option="item1" aria-activedescendant="">
  <span aria-hidden="true" data-trigger="multiselect"></span>
  <ul id="joketypes" role="listbox" aria-label="Jokes">
    <li class="active" role="option" id="item1">Puns</li>
    <li class="option" role="option" id="item2">Riddles</li>
    <li class="option" role="option" id="item3">Observations</li>
    <li class="option" role="option" id="item4">Knock-knock</li>
    <li class="option" role="option" id="item5">One liners</li>
  </ul>
</div>

Specifications

Specification
Accessible Rich Internet Applications (WAI-ARIA)
# combobox
Unknown specification
ARIA Authoring Practices
# combobox

See also