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Accessibility in JavaScript ComboBox control

27 Jul 2021 / 4 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 use 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 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 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 Open the popup list
Alt + Up Close 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 Cursor moves to before of first character in input
End Cursor moves to next of last character in input

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

Source
Preview
app.ts
index.html
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import { ComboBox } from '@syncfusion/ej2-dropdowns';

// defined the array of data
let gameList: { [key: string]: Object }[] = [
        { Id: 'Game1', Game: 'Badminton' },
        { Id: 'Game2', Game: 'Basketball' },
        { Id: 'Game3', Game: 'Cricket' },
        { Id: 'Game4', Game: 'Football' },
        { Id: 'Game5', Game: 'Golf' },
        { Id: 'Game6', Game: 'Hockey' },
        { Id: 'Game7', Game: 'Rugby' },
        { Id: 'Game8', Game: 'Snooker' },
        { Id: 'Game9', Game: 'Tennis' }
    ];

// initialize ComboBox component
let ComboBoxObject: ComboBox = new ComboBox({
    //set the data to dataSource property
    dataSource: gameList,
    //map to colum to fields
    fields: { text: 'Game', value:'Id' },
    // set placeholder to ComboBox input element
    placeholder: "Select a game",
    // set the popup list height
    popupHeight: '200px'
});

// render initialized ComboBox
ComboBoxObject.appendTo('#comboelement');

document.onkeyup = function (e) {
if (e.altKey && e.keyCode === 84 /* t */) {
    // press alt+t to focus the control.
    ComboBoxObject.focusIn();
}
};
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<!DOCTYPE html>
<html lang="en">

<head>
    <title>EJ2 ComboBox</title>
    <meta charset="utf-8" />
    <meta name="viewport" content="width=device-width, initial-scale=1.0" />
    <meta name="description" content="Typescript UI Controls" />
    <meta name="author" content="Syncfusion" />
    <link href="styles.css" rel="stylesheet" />
    <link href="//cdn.syncfusion.com/ej2/ej2-base/styles/material.css" rel="stylesheet" />
    <link href="//cdn.syncfusion.com/ej2/ej2-inputs/styles/material.css" rel="stylesheet" />
    <link href="//cdn.syncfusion.com/ej2/ej2-dropdowns/styles/material.css" rel="stylesheet" />
    <script src="https://cdnjs.cloudflare.com/ajax/libs/systemjs/0.19.38/system.js"></script>
    <script src="systemjs.config.js"></script>
</head>

<body>
    <div id='loader'>LOADING....</div>
    <div id='container' style="margin:50px auto 0; width:250px;">
        <br>
        <input type="text" tabindex="1" id='comboelement' />
    </div>
</body>

</html>
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