ARIA: textbox role - Accessibility 编辑

The textbox role is used to identify an element that allows the input of free-form text. Whenever possible, rather than using this role, use an <input> element with type="text", for single-line input, or a <textarea> element for multi-line input.

Description

When an element has the textbox role, the browser sends an accessible textbox event to assistive technologies, which can then notify the user about it.

The default is a single line input, in which Return or Enter submits the form; in this case, it is preferable to use an HTML <input> with type="text". To create a multi-line text box which supports line breaks, as in an HTML <textarea>, set aria-multiline="true". Including the HTML contenteditable attribute ensures the text node is editable.

<!-- Simple text input field -->
<div id="txtboxLabel">Enter your five-digit zipcode</div>
<div role="textbox" contenteditable="true" aria-placeholder="5-digit zipcode" aria-labelledby="txtboxLabel"></div>

<!-- Multi-line text area -->
<div id="txtboxMultilineLabel">Enter the tags for the article</div>
<div role="textbox" contenteditable="true" aria-multiline="true"
   aria-labelledby="txtboxMultilineLabel" aria-required="true"></div> 

Semantic elements are more concise and require no JavaScript to support textbox features.

<label for="txtbox">Enter your five-digit zipcode</label>
<input type="text" placeholder="5-digit zipcode" id="txtbox"/>

<!-- Multi-line text area -->
<label for="txtboxMultiline">Enter the tags for the article</label>
<textarea id="txtboxMultiline" required></textarea> 

Where a text field is read-only, indicated this by setting aria-readonly="true" on the element.

Associated ARIA properties

aria-activedescendent attribute

Taking as it's value the ID of is either a descendant of the element with DOM focus or is a logical descendant as indicated by the aria-owns attribute, it indicates when that element has focus, when it is part of a composite widget such as a combobox. For example, in a combobox, focus may remain on the textbox while the value of aria-activedescendant on the textbox element refers to a descendant of a popup listbox that is controlled by the textbox.This attribute must be updated programmatically as the focus changes.

aria-autocomplete attribute

Indicates whether and how the user's input into the field could trigger display of a prediction of the intended value. It supports the following values:

• inline: Predicted text is inserted after the caret.
• list: Predicted text is presented as a collection of values.
• both: Predicted text is presented as a collection of values, with the text needed to complete one value inserted after the caret.
• none (default): Predicted text is not offered.

If list or both is set, the aria-controls and aria-haspopup attributes should also be included. The value of aria-controls is the ID of the element that contains the list of suggested values. Additionally, either the textbox or a containing element with role combobox has a value for aria-haspopup that matches the role of the element that contains the list of suggested values.

aria-multiline attribute

If aria-multiline="true" is set, the AT informs the user that the textbox supports multi-line input, with the expectation that Enter  or Return will create a line break rather than submitting the form. ARIA does not alter the behavior of the element; rather this feature must be controlled by the developer. If false is set, or the attribute is omitted and defaults to false, the user expectation is that the control is a single line text box, and Enter  or Return submits the form.

aria-placeholder attribute

Represents a hint (word or phrase) to the user about what to enter into the text field. The hint should be a sample value or a brief description of the expected format.This information should not be used as a substitute for a label: a label is focusable, permanent, indicates what kind of information is expected, and increases the hit area for setting focus on the control, whereas placeholder text is only temporary hint about the expected value, which if implemented incorrectly can decrease accessibility. The placeholder should be visible when the control's value is the empty string such as when the control first receives focus and when users remove a previously-entered value. Instead of using aria-placeholder, use the semantic <input type="text"> or <textarea> with a placeholder attribute.

aria-readonly attribute

Indicates that the user cannot modify the value of the text field. Instead of using aria-readonly, use the semantic <input type="text"> or <textarea> with a readonly attribute.

aria-required attribute

Indicates that a value must be provided for the field before it is submitted. Instead of using aria-required, use the semantic <input type="text"> or <textarea> with a required attribute.

Keyboard interactions

In a single-line use (when aria-multiline is false or not used), the Return or Enter key submits the form. In a multi-line use (when aria-multiline is true), Return or Enter key inserts a line break.

JavaScript features

All features associated with any and all properties and states must be maintained, and forms submission on enter or return on a single line textbox needs to be handled.

Focus event handler and aria-activedescendent attribute

If you are implementing a composite widget, such as a combobox composed of a text box and a listbox, you need to manage the aria-activedescendent attribute using a handler. Before using this technique, ensure that the browsers you need to target currently support it. See the specification of aria-descendent for further information.

It is a better practice to use an <input> element with type="text", or a <textarea> element instead of the ARIA textbox role. When using either semantic element, the ARIA textbox role is not necessary. See Notes on Using ARIA in HTML.

Possible effects on user agents and assistive technology 

When the textbox role is added to an element, or such an element becomes visible, the user agent should do the following:

• Expose the element as having a textbox role in the operating system's accessibility API.
• Fire an accessible textbox event using the operating system's accessibility API if it supports it.

Assistive technology products should listen for such an event and notify the user accordingly:

• Screen readers should announce its label and role when focus first lands on a textbox. If it also contains content, this should be announced as with a regular textbox.
• Screen magnifiers may enlarge the textbox.

Note: Opinions may differ on how assistive technology should handle this technique. The information provided above is one of those opinions and therefore not normative.

Examples

Example 1: Adding the role in the HTML code for single line input

The snippet below shows how the textbox role is added directly into the HTML source code.

<div role="textbox" contenteditable="true"></div>

Example 2: Adding the role in the HTML code for multi-line input

The snippet below shows how the textbox role is added directly into the HTML source code.

<div role="textbox" contenteditable="true" aria-multiline="true"></div>

Best practices

• Be sure to add the contenteditable="true" attribute to the HTML element to which this role is applied. Do so even if you set aria-readonly to true; in this way, you communicate that the content would be editable if it were not read-only.

See also

• ARIA: search role