Chips Combobox

A quick way to add or remove chips

Prefilled chips combobox

Introduction

The chips-combobox is a composite component that combines and implements combobox and chip. It is responsible for creating and managing chip components. It allows the searching of existing selection options and manages additions/removals of chips. The search/selection follows the combobox pattern.

Terminology

• combobox: the pattern as a whole, comprised of the following distinct parts

• textbox: stores and displays the form value

• flyout: the overlay that contains a listbox

• listbox: listbox containing options

• option/suggestion: a suggestion inside of the listbox and/or directly after the textbox value

• autocomplete: the autocomplete type (optional)

• filter: the filtering criteria (optional)

• chip: the individual items inside that can be added and removed

Working Example

View a fully styled example in our eBay Skin CSS framework.

Best Practices

Since chips-combobox is a composite component and includes a combobox , it automatically inherits its pattern. For the sake of completion, here's that pattern quoted from its own page:

Each row in the list of options performs only a singular action: setting the value of the textbox. It is not possible, at the time of writing, to have additional actions per row, e.g. add, edit or delete.

The combobox listbox is not intended for storing or display kind of single-select or multi-select state. Again, the purpose of each option is to simply set the value of the textbox.

A combobox is an enhancement of textbox. Likewise, autocomplete is an enhancement of combobox. Suggestions provided will update dynamically based on user input. The suggested values may appear inline within the textbox, in a list, or both places at once.

Examples of autocomplete are the URL bar in browsers, and the main search field in search engines.

Chips

Since chips-combobox manages the addition and removal of chip(s) , they require some key elements. A chip can be static of interactive. Static chips are extremely simple and don't require much guidance. Here, we will only be looking at interactive chips. Here's the markup for each chip:

<span class="chip">
    <span id="chip-interactive-1-1-text" class="chip__text">Football</span>
    <button class="chip__button" type="button" aria-label="Remove" aria-describedby="chip-interactive-1-1-text">
        <svg class="icon icon--close-12" width="13" height="12" aria-hidden="true">
            <use href="#icon-close-12"></use>
        </svg>
    </button>
</span>

Each chip has a button inside that removes the chip from the chips-combobox . The chip__text needs an id that is used by the button via aria-describedby to link the button removal to the specific chip.

The close svg icon for each chip needs to have aria-hidden="true" since its function is conveyed by the button.

Interaction Design

Since chips combobox is a composite component and includes a combobox , it automatically inherits its interaction design. Once again, here's that pattern quoted from its own page:

Keyboard

When the combobox receives focus, the listbox should expand to show all options.

With listbox expanded, pressing DOWN-ARROW and UP-ARROW keys must navigate through the list of options. The keyboard focus will appear to be in two places at the same time - the textbox and the listbox. In actual fact, keyboard focus always stays on the textbox. The aria-activedescendant property controls the pseudo-focus inside of the listbox.

Pressing SPACEBAR must always enter a blank space in the textbox.

For a combobox with autoSelect, changing the highlighted option will automatically fill the textbox with that option.

For a combobox without autoSelect, changing the highlighted option must not automatically fill the textbox; ENTER key is required to manually select the option.

Pressing ENTER key while an option is highlighted must collapse the listbox. For a combobox with autoSelect the form will be submitted. For a combobox without autoSelect the form must not be submitted.

Pressing ESC key while an option is highlighted must collapse the listbox.

For autocomplete type "list":

The listbox remains but the options change based on the custom filtering criteria.

With focus in the empty combobox, type any letter. Any suggestions that match the filter will appear as options in the listbox flyout.

For autocomplete type "inline":

The listbox is removed. The entire combobox value will update as the user types, with the suggested portion highlighted as a selection range.

For autocomplete type "both":

This section is under development.

Screen Reader

The screen reader will announce the input as "text edit", "combobox" or words to those effect, depending on level of ARIA support.

The screen reader will announce "expanded" or "collapsed", depending on level of ARIA support.

The screen reader will announce any additional programmatic description, depending on level of ARIA support.

The screen reader will announce the current value of the textbox.

Mouse and Touch

When the combobox receives focus, via click or tap, the listbox should expand to show all options.

Clicking or tapping an option will fill the textbox with that value and collapse the listbox without triggering a form submit.

In addition, there is interaction between the combobox and chip items.

Chip Creation with Keyboard and Mouse

As the user has gained focus of the textbox, the listbox will display to show all available options. As the user types, the listbox will be filtered to display only items meeting the criteria of the entered text. Consistent with a typical combobox, the user would then use the arrow keys to navigate to the item they'd like to add. Pressing ENTER when the indicator is on a specific item, will create a chip with that item. Utilizing a mouse, when the user clicks on any of the items in the listbox, a chip will be created for that item.

Custom Chip Creation

A custom chip can be created only with the keyboard. As the user types inside the textbox, at any given moment, pressing ENTER will create a chip with/for the text present in the textbox.

Patterns to Avoid: Comma

There may be a tendency to consider using a comma(,) to fire off the creation of a chip. The current guidance is to avoid doing so. Commas are too specific in usage on certain platforms and do not have as wide of an intuitive base of accepted usage patterns. Conversely, ENTER is a universally accepted pattern for submission of an entry.

States

Rest State

Open State

Filled State

Disabled State

Error State

Usage of the error state requires the addition of the field error state.

Developer Guide

For the sake of comprehensive coverage, once again, the portions relevant to the combobox are quoted from its developer guide:

Textbox

We start with a label and textbox.

<span class="combobox" id="combobox-0">
  <label for="combobox-0-input">Game Console</label>
  <input id="combobox-0-input" name="console" type="text" placeholder="Playstation 4, Xbox One, etc."/>
  <!-- listbox options will go here -->
</span>

We have added our elements inside of a .combobox wrapper element. This wrapper acts as our module root and hook for CSS & JavaScript.

Remember: the textbox does not yet have a role of combobox, it is added later with JavaScript.

A listbox element will be appended to this wrapper. It is up to you whether you wish to render this server-side or client-side. There are pros and cons to both approaches, which we will discuss below.

Listbox

The listbox may render on the server or the client. It is wise to put the listbox in a hidden state if rendering on the server. To do so, use the hidden attribute.

<div class="combobox__overlay" hidden>
  <ul id="combobox_0-listbox" role="listbox">
    <li role="option" id="nid-0">Playstation 3</li>
    <li role="option" id="nid-1">Playstation 4</li>
    <li role="option" id="nid-2">Xbox 360</li>
    <li role="option" id="nid-3">Xbox One</li>
    <li role="option" id="nid-4">Wii</li>
    <li role="option" id="nid-5">Wii U</li>
  </ul>
</div>

Using JavaScript we now begin converting the textbox to a combobox, by adding role=combobox. We also create the properties and state that connect the combobox to the listbox:

<input id="combobox-0-input" name="console0" type="text" placeholder="Playstation 4, Xbox One, etc." role="combobox" aria-expanded="false" autocomplete="off" aria-owns="combobox_0-listbox">

The new attributes are role, aria-expanded, autocomplete and aria-owns.

Description

At the time of writing, screen readers don't do a good job of conveying the combobox role or how to interact with it. To solve this problem, we can add a description via aria-roledescription.

<input aria-roledescription="Use up and down arrow keys to navigate combobox options" id="combobox-0-input" name="console0" type="text" placeholder="Playstation 4, Xbox One, etc." role="combobox" aria-expanded="false" autocomplete="off" aria-owns="combobox_0-listbox">

Now the screen reader announces the description whenever focus lands on the combobox.

If the number of options will change based on the value of the combobox (i.e. filtering occurs), the description should also make the user aware of this:

<input aria-roledescription="Use up and down arrow keys to navigate combobox options. Combobox options may change based on input." id="combobox-0-input" name="console0" type="text" placeholder="Playstation 4, Xbox One, etc." role="combobox" aria-expanded="false" autocomplete="off" aria-owns="combobox_0-listbox"/>

Keyboard and Screen Reader Navigation

Our elements are now in place, but how does a keyboard user navigate to the options? We cannot use TAB key because focus must stay on the combobox (so that user can type and enter their own value). As with most complex widgets, the answer lies in the arrow keys. Up and down arrow keys are the way to select our combobox options.

If focus must remain on the combobox, how then do we also have focus on the listbox options? The answer is that we don't. Focus always remains on the combobox and instead we have a kind of pseudo-focus on the options.

How does the screen reader know where this pseudo-focus is?

Active Descendant

We call the option with pseudo-focus the "active descendant". And guess what, there is an ARIA attribute for this called aria-activedescendant. This attribute is placed on the combobox element. The attribute value is the ID of the currently active (pseudo-focussed) option. This allows assistive technology such as a screen reader to programmatically determine

To make all of this easier, we recommend using a plugin such as makeup-active-descendant. After your HTML structure is in place, simply initialise the plugin on the widget and up/down arrow keys will update the necessary states. Use CSS to style the active descendant in any way you like.

ARIA Reference

This section gives an overview of ARIA usage, within the context of this pattern.

role=combobox

This attribute changes the role of the text input from textbox to combobox. We recommend applying this attribute on the client-side with JavaScript.

aria-roledescription

Gives additional instructions on how to operate the combobox options.

role=listbox

The list of suggestions has a role of listbox.

role=option

Each listbox item has a role of option.

aria-owns

This property creates a programmatic hierarchy in the accessibility tree for the combobox and the listbox.

aria-expanded

Conveys the expanded state of the combobox.

aria-label

Provides the expand/collapse button with an accessible label, in the case where it has no visible text (i.e. an icon button). It also provides an accessible label for the chips-combobox unordered list:

<ul class="chips-combobox__items" aria-label="Selected sports">...

aria-labeledby

In instances where a heading or label is provided before the chips-combobox, it can link to the element for its aria label:

<h2 id="sports-chips-combobox">Sports</h2>
<span class="chips-combobox">
    <ul class="chips-combobox__items" aria-labeledby="sports-chips-combobox"></ul>
    <span class="combobox combobox--js chips-combobox__combobox">
        <span class="combobox__control chips-combobox_combobox__control">
            <input id="chips-combobox-1-input" role="combobox" type="text" placeholder="Add Sport" aria-haspopup="listbox" aria-owns="listbox-chips-combobox-1" />
            <svg class="icon icon--chevron-down-16" height="16" width="16" aria-hidden="true">
                <use href="#icon-chevron-down-16"></use>
            </svg>
        </span>
        <div class="combobox__listbox">
            <div id="listbox-chips-combobox-1" class="combobox__options" role="listbox">
                <div class="combobox__option" role="option">
                    <span>Soccer</span>
                </div>
                <div class="combobox__option" role="option">
                    <span>Hockey</span>
                </div>
                <div class="combobox__option" role="option">
                    <span>Tennis</span>
                </div>
            </div>
        </div>
    </span>
</span>