ARIA: checkbox role - Accessibility 编辑

The checkbox role is used for checkable interactive controls. Elements containing role="checkbox" must also include the aria-checked attribute to expose the checkbox's state to assistive technology.

<span role="checkbox" aria-checked="false" tabindex="0" aria-labelledby="chk1-label">
</span> <label id="chk1-label">Remember my preferences</label>

The first rule of ARIA is if a native HTML element or attribute has the semantics and behavior you require, use it instead of re-purposing an element and adding ARIA. Instead use the native HTML checkbox of <input type="checkbox">, which natively provides all the functionality required:

<input type="checkbox" id="chk1-label">
<label for="chk1-label">Remember my preferences</label>

Description

The native HTML checkbox  form control can only have two checked states ("checked" or "not checked"), with an indeterminate state settable via JavaScript. Similarly, an element with role="checkbox"  can expose three states through the aria-checked attribute: true, false, or mixed.

Since a checkbox is an interactive control, it must be focusable and keyboard accessible. If the role is applied to a non-focusable element, use the tabindex attribute to change this. The expected keyboard shortcut for activating a checkbox is the Space key.

The developer is required to change the value of the aria-checked attribute dynamically when the checkbox is activated.

Associated WAI-ARIA Roles, States, and Properties

aria-checked

The value of aria-checked defines the state of a checkbox. This attribute has one of three possible values:

true
    The checkbox is checked
false
    The checkbox is not checked
mixed
    The checkbox is partially checked, or indeterminate

tabindex="0"

Used to make it focusable so the assistive technology user can tab to it and start reading right away.

Keyboard interactions

Required JavaScript

Required event handlers

onclick

Handle mouse clicks that will change the state of the checkbox by changing the value of the aria-checked attribute and the appearance of the checkbox so it appears checked or unchecked to the sighted user

onKeyPress

Handle the case where the user presses the Space key to change the state of the checkbox by changing the value of the aria-checked attribute and the appearance of the checkbox so it appears checked or unchecked to the sighted user

Examples

The following example creates a simple checkbox element using CSS and JavaScript to handle the checked or unchecked status of the element.

HTML

<span role="checkbox" id="chkPref" aria-checked="false" onclick="changeCheckbox()" onKeyPress="changeCheckbox()"
   tabindex="0" aria-labelledby="chk1-label"></span>
<label id="chk1-label" onclick="changeCheckbox()" onKeyPress="changeCheckbox()">Remember my preferences</label>

CSS

[role="checkbox"] {
    padding:5px;
}

[aria-checked="true"]::before {
    content: "[x]";
}

[aria-checked="false"]::before {
    content: "[ ]";
}

JavaScript

function changeCheckbox(event) {
    let item = document.getElementById('chkPref');
    switch(item.getAttribute('aria-checked')) {
        case "true":
            item.setAttribute('aria-checked', "false");
            break;
        case "false":
            item.setAttribute('aria-checked', "true");
            break;
    }
}

Accessibility concerns

When the checkbox role is added to an element, the user agent should do the following:

• Expose the element as having a checkbox role in the operating system's accessibility API.
• When the aria-checked value changes, send an accessible state changed event.

Assistive technology products should do the following:

• Screen readers should announce the element as a checkbox, and optionally provide instructions on how to activate it.

Best practices

The first rule of ARIA is: if a native HTML element or attribute has the semantics and behavior you require, use it instead of re-purposing an element and adding an ARIA role, state or property to make it accessible. As such, it is recommended to use the native HTML checkbox  using form control instead of recreating a checkbox's functionality with JavaScript and ARIA.

See also

• <input type="checkbox">
• ARIA: radio role
• ARIA: menuitem role
• ARIA: menuitemcheckbox role
• ARIA: menuitemradio role
• ARIA: switch role
• ARIA: option role