Accessibility in Blazor ComboBox Component

5 May 20259 minutes to read

The Blazor ComboBox component has been designed with the WAI-ARIA specifications in mind, 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 use assistive technologies (AT) or those who completely rely on keyboard navigation.

The Blazor ComboBox component followed the accessibility guidelines and standards, including ADA, Section 508, WCAG 2.2 standards, and WCAG roles that are commonly used to evaluate accessibility.

The accessibility compliance for the Blazor ComboBox component is outlined below.

Accessibility Criteria Compatibility
WCAG 2.2 Support Yes
Section 508 Support Yes
Screen Reader Support Yes
Right-To-Left Support Yes
Color Contrast Yes
Mobile Device Support Yes
Keyboard Navigation Support Yes
Axe-core Accessibility Validation Yes
Yes - All features of the component meet the requirement.
Intermediate - Some features of the component do not meet the requirement.
No - The component does not meet the requirement.

WAI-ARIA attributes

The Blazor ComboBox component uses the combobox role, and each list item has an option role. The following ARIA attributes denotes 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 has 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 Blazor ComboBox without interruptions:

Windows Mac Actions
Focus    
Alt + J ⌥ + J Focuses on the first component of the sample.
Input Navigation    
Alt + ↓ ⌥ + ↓ Opens the popup list.
Alt + ↑ ⌥ + ↑ Closes the popup list.
Home Home Cursor moves before the first character in the input.
End End Cursor moves before the last character in the input.
Tab 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 ⇧ + 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.
Selection    
Enter Enter Selects the focused item, and when it is in open state, the popup list closes. Otherwise, toggles the popup list.
Popup Navigation    
Esc(Escape) Escape Closes the popup list when it is in an open state and the currently selected item remains the same.
↓ ↓ Selects the first item in the ComboBox when no item is selected. Otherwise, selects the item next to the currently selected item.
↑ ↑ Selects the item previous to the currently selected one.
Page down Page down Scrolls down to the next page and selects the first item when the popup list opens.
Page up Page up Scrolls up to the previous page and selects the first item when the popup list opens.

NOTE

In the following sample, disable the ComboBox component using t keys.

@using Syncfusion.Blazor.DropDowns

<SfComboBox TValue="string" TItem="Country" @ref="ComboObj" Enabled="@enable" Placeholder="Select a country" @onkeypress="@(e => KeyPressed(e))" DataSource="@LocalData">
    <ComboBoxFieldSettings Value="Code" Text="Name"></ComboBoxFieldSettings>
</SfComboBox>

@code {

    public SfComboBox<string, Country> ComboObj;

    public bool enable { get; set; } = true;
    public class Country
    {
        public string Name { get; set; }
        public string Code { get; set; }
    }

    List<Country> LocalData = new List<Country> {
        new Country() { Name = "Australia", Code = "AU" },
        new Country() { Name = "Bermuda", Code = "BM" },
        new Country() { Name = "Canada", Code = "CA" },
        new Country() { Name = "Cameroon", Code = "CM" },
        new Country() { Name = "Denmark", Code = "DK" },
        new Country() { Name = "France", Code = "FR" },
        new Country() { Name = "Finland", Code = "FI" },
        new Country() { Name = "Germany", Code = "DE" },
        new Country() { Name = "Greenland", Code = "GL" },
        new Country() { Name = "Hong Kong", Code = "HK" },
    };

    public void KeyPressed(KeyboardEventArgs args)
    {
        if (args.Key == "t")
        {
            enable = false;
        }
    }
}

Ensuring accessibility

The Blazor ComboBox component’s accessibility levels are ensured through an axe-core software tool during automated testing.

The accessibility compliance of the ComboBox component is shown in the following sample. Open the sample in a new window to evaluate the accessibility of the ComboBox component with accessibility tools.

See also