ARIA: combobox role

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 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 can be set on either an input element for editable comboboxes, or a button element for select-only comboboxes. This element controls another element, such as a listbox or grid, that can dynamically pop up to help the user set a value.

The element with the combobox role can be either an editable single-line text field (using an <input> element, similar to one with a <datalist>), or a select-only element (using a button element) that only displays the current value without allowing direct text input.

A WAI-ARIA combobox requires only one attribute: aria-expanded. However, several other attributes are typically necessary depending on the implementation: 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 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 is implemented as an editable <input> element, the value of the combobox is the input's value. For select-only comboboxes implemented with a button element, the value comes from the selected option in the popup.

The aria-autocomplete attribute is only applicable for editable comboboxes that support text input. For these comboboxes, set the attribute to a value that corresponds to the provided behavior: inline, list, or both. The attribute indicates that inputting text will trigger display of one or more predictions of the user's intended value and specifies how these predictions will be presented. For select-only comboboxes using a button element, aria-autocomplete should not be used since no text input is possible.

Every combobox must have an accessible name, which can be provided in one of three ways:

1. For an <input> element, use an associated <label>.
2. If a visible label exists in the UI, use aria-labelledby referencing the label element's id.
3. If no visible label is present, use aria-label.

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

Opens the popup if closed and 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

Opens the popup if closed and moves focus to the previous option, or to the last option if none was selected.

Alt + Up Arrow (Optional)

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

Escape

Closes the popup if open. If the popup is already closed, clears the combobox value for editable comboboxes.

Editable combobox keyboard interactions

Enter

If an autocomplete suggestion is selected in the popup, accepts the suggestion by updating the combobox value and placing the input cursor at the end. May also trigger a default action (e.g., in a messaging application, adding the accepted value to a list of recipients).

Tab

Accepts the current value and moves focus to the next focusable element.

Select-only combobox keyboard interactions

Enter or Space

When the popup is closed, opens the popup. When the popup is open and an option is selected, accepts the selected option as the combobox value and closes the popup.

Tab

Accepts the current selection and moves focus to the next focusable element.

Home or End

When the popup is open, moves focus to the first or last option respectively.

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

See also

• HTML <label> element
• HTML <select> element
• HTML <option> element
• HTML <input> element
• ARIA: listbox role
• ARIA: option role
• ARIA: list role
• ARIA: listitem role
• ARIA Best Practices – Combobox
• Accessible combobox module examples by Deque