Accessibility in ASP.NET MVC ComboBox

18 Nov 20188 minutes to read

The ComboBox component has been designed, keeping in mind the WAI-ARIA specifications, and applies the WAI-ARIA roles, states, and properties along with keyboard support. This component is characterized by complete keyboard interaction support and ARIA accessibility support that makes it easy for people who uses assistive technologies (AT) or those who completely rely on keyboard navigation.

ARIA attributes

The ComboBox component uses the combobox role, and each list item has an option role. The following
ARIA attributes denote the ComboBox state.

Properties	Functionalities
aria-haspopup	Indicates whether the ComboBox input element has a popup list or not.
aria-expanded	Indicates whether the popup list is expanded or not.
aria-selected	Indicates the selected option.
aria-readonly	Indicates the readonly state of the ComboBox element.
aria-disabled	Indicates whether the ComboBox component is in a disabled state or not.
aria-activedescendent	This attribute holds the ID of the active list item to focus its descendant child element.
aria-owns	This attribute contains the ID of the popup list to indicate popup as a child element.
aria-autocomplete	This attribute contains the ‘both’ to a list of options shows and the currently selected suggestion also shows inline.

Keyboard interaction

You can use the following key shortcuts to access the ComboBox without interruptions.

Keyboard shortcuts	Actions
Arrow Down	Selects the first item in the ComboBox when no item selected. Otherwise, selects the item next to the currently selected item.
Arrow Up	Selects the item previous to the currently selected one.
Page Down	Scrolls down to the next page and selects the first item when popup list opens.
Page Up	Scrolls up to the previous page and selects the first item when popup list opens.
Enter	Selects the focused item and popup list closes when it is in open state.
Tab	Focuses on the next TabIndex element on the page when the popup is closed. Otherwise, closes the popup list and remains the focus of the component.
Shift + tab	Focuses on the previous TabIndex element on the page when the popup is closed. Otherwise, closes the popup list and remains the focus of the component.
Alt + Down	Opens the popup list.
Alt + Up	Closes the popup list.
Esc(Escape)	Closes the popup list when it is in an open state and the currently selected item remains the same.
Home	Selects the first item when popup open state. If it is in closed state, cursor moves to before of first character in input
End	Selects the last item when popup open state. If it is in closed state, cursor moves to next of last character in input

In the following sample, focus the ComboBox component using the alt+t keys.

HTML

<div class="frame">
        <div class="control">
            @{
                Html.EJ()
                    .ComboBox("groupingCountry")
                    .Datasource((IEnumerable<Countries>)ViewBag.datasource)
                    .Width("100%")
                    .ComboBoxFields(fields => fields.Text("text"))
                    .Placeholder("Select a country")
                    .Render();
            }
        </div>
    </div>
<script type="text/javascript">
   
    $(function () {
        $(document).on("keydown", function (e) {
            if (e.altKey && e.keyCode === 84 /* t */) {
                // press alt+t to focus the control.
               $("#groupingCountry").focus();
            }
        });

    });
</script>

C#

public string text { get; set; }
        public string category { get; set; }
        public static List<Countries> GetCountries()
        {
            List<Countries> country = new List<Countries>();
            country.Add(new Countries { text = "Austria", category = "A" });
            country.Add(new Countries { text = "Australia", category = "A" });
            country.Add(new Countries { text = "Antarctica", category = "A" });
            country.Add(new Countries { text = "Bangladesh", category = "B" });
            country.Add(new Countries { text = "Brazil", category = "B" });
            country.Add(new Countries { text = "Canada", category = "C" });
            country.Add(new Countries { text = "Cuba", category = "C" });
            country.Add(new Countries { text = "Denmark", category = "D" });
            country.Add(new Countries { text = "Dominica", category = "D" });
            return country;
        }
    }
}

Output for accessibility ComboBox control is as follows.