autocomplete attribute has valid value

  • Rule Type:atomic
  • Rule Id: 73f2c2
  • Last modified: Sep 29, 2020
  • Accessibility Requirements Mapping:
    • 1.3.5 Identify Input Purpose (Level AA)
      • Learn More about 1.3.5 Identify Input Purpose
      • Required for conformance to WCAG 2.1 on level AA and higher.
      • Outcome mapping:
        • Any failed outcomes: success criterion is not satisfied.
        • All passed outcomes: success criterion needs further testing.
        • An inapplicable outcome: success criterion needs further testing.

Description

This rule checks that the HTML autocomplete attribute has a correct value.

Applicability

The rule applies to any HTML input, select and textarea element with an autocomplete attribute value that is neither empty ("") nor only ASCII whitespace, except if one of the following is true:

Expectation 1

Each test target's autocomplete attribute value is a space separated list of one or more tokens that follow the HTML specification for Autofill detail tokens, which requires that the token list match the following in the correct order:

  1. An optional token that starts with "section-"; then
  2. An optional token of either "shipping" or "billing"; then
  3. An optional token of either "home", "work", "mobile", "fax" or "pager", only if the last token is "email", "impp", "tel" or "tel-*"; then
  4. A required token from the correct autocomplete field.

Expectation 2

Each test target's autocomplete attribute value has a correct autocomplete field that is appropriate for that test target.

Assumptions

The autocomplete attribute is used on form fields that correspond to Input Purposes for User Interface Components and collect information about the user.

If the autocomplete field is used to describe "custom" taxonomy, rather than that described in the list of input purposes, or the form fields do not collect information about the user, success Criterion 1.3.5 Identify Input Purpose may be satisfied even if this rule failed.

The type attribute is used correctly according to the intended purpose of input elements. If an incorrect type attribute is used for input elements, this rule may fail elements that satisfy success Criterion 1.3.5 Identify Input Purpose. For example if an input element has a type of number, but is expecting an e-mail address.

The aria-disabled state is used on input elements which are not part of sequential focus navigation and are not otherwise operable. If this is not the case, this rule may be inapplicable on elements that are still operable and require a valid autocomplete attribute to satisfy success Criterion 1.3.5 Identify Input Purpose.

Accessibility Support

  • While autocomplete is a promising technique for supporting personalization in HTML, support for this in assistive technologies is fairly limited.
  • Implementation of Presentational Roles Conflict Resolution varies from one browser or assistive technology to another. Depending on this, some elements can have a semantic role of none and fail this rule with some technology but users of other technologies would not experience any accessibility issue.
  • Some user agents treat the value of the aria-disabled attribute as case-sensitive.
  • In some user agents, querying the value of the autocomplete property returns an empty string ("") even when the attribute was set according to the rule's expectations. It affects assistive technologies which rely on this property to personalize input fields collecting information about the user.

Background

The intent of this rule is to ensure that the autocomplete attribute can be used to support personalization. Many users may find it easier to fill out forms if those can be styled or laid out in a way that is familiar to them. Assistive technologies can do this when a form control is marked up in such a way that its purpose can be understood. For instance, assistive technologies could add familiar icons and colors to different fields, making it easier for the user to understand what the form does.

The auto-completing feature of the autocomplete attribute benefits many users, but it is not required to satisfy success Criterion 1.3.5 Identify Input Purpose. Setting autocomplete="off" on the element's form owner prevents the user agent from completing it, but it does not prevent the autocomplete attribute value from being programmatically identifiable.

Test Cases

Passed

Passed Example 1

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This autocomplete attribute value only has the required token, and is valid for an input element which has a default type of text.

<label>Username<input autocomplete="username"/></label>

Passed Example 2

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This autocomplete attribute value only has the required token, and is valid for a select element. Even though the element's form owner has autocomplete="off", thus preventing the user agent from completing it, it does not prevent the autocomplete attribute value from being programmatically identifiable.

<form autocomplete="off">
	<select autocomplete="bday-month">
		<option>January</option>
		<option>...</option>
	</select>
</form>

Passed Example 3

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This autocomplete attribute value only has the required token, and is valid for a textarea element. Mixing upper and lower case letters is allowed for autocomplete attributes.

<textarea autocomplete="Street-Address"></textarea>

Passed Example 4

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This autocomplete attribute value list includes a work token, allowed because it is used before email. The email token is allowed on input elements with a type attribute value of text.

<label>Work email<input autocomplete="Work Email"/></label>

Passed Example 5

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This autocomplete attribute value list includes a section- token, which can preface any correct autocomplete field. The email token is allowed on input elements with a type attribute value of text.

<label>Email<input autocomplete="section-partner email"/></label>

Passed Example 6

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This autocomplete attribute value list includes section- and billing tokens. These tokens can preface any correct autocomplete field.

<label>Address<input type="text" autocomplete="section-primary billing address-line1"/></label>

Passed Example 7

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This autocomplete attribute value list includes all allowed types of tokens in the correct order. The email token is allowed on input elements with a type attribute value of text.

<label>Email<input type="text" autocomplete="section-primary shipping work email"/></label>

Passed Example 8

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The autocomplete attribute value is on an input element that does not have a semantic role that is a widget role, but still participates in sequential focus navigation because of the tabindex attribute.

<label>Username<input role="banner" tabindex="0" autocomplete="username"/></label>

Failed

Failed Example 1

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This autocomplete attribute value has an unknown term that is not a correct autocomplete field.

<label>Username<input autocomplete="badterm"/></label>

Failed Example 2

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This autocomplete attribute value has the work token on a correct autocomplete field, however work can not be used with photo.

<label>Photo<input autocomplete="work photo"/></label>

Failed Example 3

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This autocomplete attribute value includes the work token before the shipping token, instead of the other way around.

<label>Email<input autocomplete="work shipping email"/></label>

Failed Example 4

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This autocomplete attribute value is comma separated instead of space using ASCII whitespace.

<label>Email<input autocomplete="work,email"/></label>

Failed Example 5

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This autocomplete attribute value is not appropriate for the field. The form field's implied purpose is to input a quantity (a number) which cannot be a e-mail.

<label>Quantity<input type="number" autocomplete="email"/></label>

Inapplicable

Inapplicable Example 1

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This button element does not support autocomplete attributes.

<button autocomplete="username"></button>

Inapplicable Example 2

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This autocomplete attribute value is empty ("").

<label>Username<input autocomplete=""/></label>

Inapplicable Example 3

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This autocomplete attribute value contains only ASCII whitespace.

<label>Username<input autocomplete=" "/></label>

Inapplicable Example 4

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This autocomplete attribute value is on an element that is not visible through display:none.

<label>Username<input autocomplete="username" style="display:none"/></label>

Inapplicable Example 5

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This autocomplete attribute is on an input element with a type attribute value that does not support autocomplete.

<label>Username<input type="button" autocomplete="username"/></label>

Inapplicable Example 6

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This autocomplete attribute is on an input element that has the disabled attribute.

<label>Username<input autocomplete="username" disabled/></label>

Inapplicable Example 7

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This autocomplete attribute is on an input element that has the aria-disabled attribute value of true.

<label>Username<input autocomplete="username" aria-disabled="true"/></label>

Inapplicable Example 8

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This autocomplete attribute is ignored because it is on an element with a semantic role of none. The disabled attribute is required to ensure presentational roles conflict resolution does not cause the none role to be ignored.

<label>Username<input type="text" role="none" disabled autocomplete="username"/></label>

Glossary

Attribute value

The attribute value of a content attribute set on an HTML element is the value that the attribute gets after being parsed and computed according to specifications. It may differ from the value that is actually written in the HTML code due to trimming whitespace or non-digits characters, default values, or case-insensitivity.

Some notable case of attribute value, among others:

  • For enumerated attributes, the attribute value is either the state of the attribute, or the keyword that maps to it; even for the default states. Thus <input type="image" /> has an attribute value of either Image Button (the state) or image (the keyword mapping to it), both formulations having the same meaning; similarly, "an input element with a type attribute value of Text" can be either <input type="text" />, <input /> (missing value default), or <input type="invalid" /> (invalid value default).
  • For boolean attributes, the attribute value is true when the attribute is present and false otherwise. Thus <button disabled>, <button disabled="disabled"> and <button disabled=""> all have a disabled attribute value of true.
  • For attributes whose value is used in a case-insensitive context, the attribute value is the lowercase version of the value written in the HTML code.
  • For attributes that accept numbers, the attribute value is the result of parsing the value written in the HTML code according to the rules for parsing this kind of number.
  • For attributes that accept sets of tokens, whether space separated or comma separated, the attribute value is the set of tokens obtained after parsing the set and, depending on the case, converting its items to lowercase (if the set is used in a case-insensitive context).
  • For aria-* attributes, the attribute value is computed as indicated in the WAI-ARIA specification.

This list is not exhaustive, and only serves as an illustration for some of the most common cases.

The attribute value of an IDL attribute is the value returned on getting it. Note that when an IDL attribute reflects a content attribute, they have the same attribute value.

Explicit Semantic Role

The explicit semantic role of an element is determined by its role attribute (if any).

The role attribute takes a list of tokens. The explicit semantic role is the first valid role in this list. The valid roles are all non-abstract roles from WAI-ARIA Specifications. If the element has no role attribute, or if it has one with no valid role, then this element has no explicit semantic role.

Other roles may be added as they become available. Not all roles will be supported in all assistive technologies. Testers are encouraged to adjust which roles are allowed according to the accessibility support base line. For the purposes of executing test cases in all rules, it should be assumed that all roles are supported by assistive technologies so that none of the roles fail due to lack of accessibility support.

Accessibility Support for Explicit Semantic Role

Some browsers and assistive technologies treat the tokens of the role attribute as case-sensitive. Unless lowercase letters are used for the value of the role attribute, not all user agents will be able to interpret the tokens correctly. ARIA in HTML (working draft) also specifies that authors must use lowercase letters for the role and aria-* attributes.

Hidden State

An HTML element's hidden state is "true" if at least one of the following is true for itself or any of its ancestors in the flat tree:

  • has a hidden attribute; or
  • has a computed CSS property display of none; or
  • has a computed CSS property visibility of hidden; or
  • has an aria-hidden attribute set to true

In any other case, the element's hidden state is "false".

Implicit Semantic Role

The implicit semantic role of an element is a pre-defined value given by the host language which depends on the element and its ancestors.

Implicit roles for HTML and SVG, are documented in the HTML accessibility API mappings (working draft) and the SVG accessibility API mappings (working draft).

Accessibility Support for Implicit Semantic Role

  • Images with an empty alt attribute should have an implicit role of presentation, according to the HTML Accessibility API Mapping (work in progress). However, there are several popular browsers that do not treat images with empty alt attribute as having a role of presentation. Instead, they add the img element to the accessibility tree with a role of either img or graphic.

Included in the accessibility tree

Elements included in the accessibility tree of platform specific accessibility APIs. Elements in the accessibility tree are exposed to assistive technologies, allowing users to interact with the elements in a way that meet the requirements of the individual user.

The general rules for when elements are included in the accessibility tree are defined in the core accessibility API mappings. For native markup languages, such as HTML and SVG, additional rules for when elements are included in the accessibility tree can be found in the HTML accessibility API mappings (working draft) and the SVG accessibility API mappings (working draft).

For more details, see examples of included in the accessibility tree.

Note: Users of assistive technologies might still be able to interact with elements that are not included in the accessibility tree. An example of this is a focusable element with an aria-hidden attribute with a value of true. Such an element could still be interacted using sequential keyboard navigation regardless of the assistive technologies used, even though the element would not be included in the accessibility tree.

Marked as decorative

An element is marked as decorative if one of the following conditions is true:

  • it has an explicit role of none or presentation; or
  • it is an img element with an alt attribute whose value is the empty string (alt=""), and with no explicit role.

Elements are marked as decorative as a way to convey the intention of the author that they are pure decoration. It is different from the element actually being pure decoration as authors may make mistakes. It is different from the element being effectively ignored by assistive technologies as rules such as presentational roles conflict resolution may overwrite this intention.

Elements can also be ignored by assistive technologies if their hidden state is true. This is different from marking the element as decorative and does not convey the same intention. Notably, the hidden state of an element may change as users interact with the page (showing and hiding elements) while being marked as decorative should stay the same through all states of the page.

Outcome

An outcome is a conclusion that comes from evaluating an ACT Rule on a test subject or one of its constituent test target. An outcome can be one of the three following types:

  • Inapplicable: No part of the test subject matches the applicability
  • Passed: A test target meets all expectations
  • Failed: A test target does not meet all expectations

Note: A rule has one passed or failed outcome for every test target. When there are no test targets the rule has one inapplicable outcome. This means that each test subject will have one or more outcomes.

Note: Implementations using the EARL10-Schema can express the outcome with the outcome property. In addition to passed, failed and inapplicable, EARL 1.0 also defined an incomplete outcome. While this cannot be the outcome of an ACT Rule when applied in its entirety, it often happens that rules are only partially evaluated. For example, when applicability was automated, but the expectations have to be evaluated manually. Such "interim" results can be expressed with the incomplete outcome.

Semantic Role

The semantic role of an element is determined by the first of these cases that applies:

  1. Conflict If the element is marked as decorative, but the element is included in the accessibility tree; or would be included in the accessibility tree when its hidden state is false, then its semantic role is its implicit role.
  2. Explicit If the element has an explicit role, then its semantic role is its explicit role.
  3. Implicit The semantic role of the element is its implicit role.

Accessibility Support for Definition of Semantic Role for Semantic Role

  • There exist popular web browsers and assistive technologies which do not correctly implement Presentational Roles Conflict Resolution. These technologies will not include in the accessibility tree elements that should be, according to Specifications. Thus, some elements that should have their semantic role fixed by case Conflict above are instead falling into case Explicit and are hidden for users of assistive technologies.
  • A similar conflict exists for focusable elements with a aria-hidden="true" attribute. The WAI ARIA specification does not explain how to solve it. Some browsers give precedence to the element being focusable (and expose it in the accessibility tree) while some give precedence to the aria-hidden attribute (and hide the element).

Visible

Content perceivable through sight.

Content is considered visible if making it fully transparent would result in a difference in the pixels rendered for any part of the document that is currently within the viewport or can be brought into the viewport via scrolling.

Content is defined in WCAG.

For more details, see examples of visible.


Useful Links


Implementations

This section is not part of the official rule. It is populated dynamically and not accounted for in the change history or the last modified date. This section will not be included in the rule when it is published on the W3C website.

ToolConsistencyCompleteReport
axe-coreconsistentYesView Report
QualWebconsistentYesView Report
AlfaconsistentNoView Report
SortSiteconsistentNoView Report

Acknowledgments

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