Error message describes invalid form field value

  • Rule Type:atomic
  • Rule Id: 36b590
  • Last modified: Jun 19, 2020
  • Accessibility Requirements Mapping:
    • 3.3.1 Error Identification (Level A)
      • Learn More about 3.3.1 Error Identification
      • Required for conformance to WCAG 2.0 and later on level A 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 text error messages provided when the user completes a form field with invalid values or using an invalid format, identify the cause of the error or how to fix the error.

Applicability

The rule applies to each HTML element that has one of the following semantic roles:

  • checkbox,
  • combobox,
  • listbox,
  • menuitemcheckbox,
  • menuitemradio,
  • radio,
  • searchbox,
  • slider,
  • spinbutton,
  • switch or
  • textbox.

Note: The list of applicable semantic roles is derived by taking all the ARIA 1.1 roles that:

Expectation 1

Each test target either has no form field error indicators, or at least one of the form field error indicators allows the identification of the related test target, through text, or through non-text content, or through presentation.

Note: This rule does not test form field error indicators shown on a different page than that of the test target.

Note: A single form field error indicator can be related to multiple test targets. For example, an error message at the top of a form can list all the form fields that are required and are empty.

Note: A single test target can be related to multiple form field error indicators. For example, a text field can have a red border around it, an error icon adjacent to it, an error message below it, and another error message at the top of the form. All of these are error indicators for the same form field.

Expectation 2

Each test target either has no form field error indicators, or at least one of the form field error indicators describes:

  • the cause of the error, or
  • how to resolve it,

in text that is visible.

Expectation 3

Each test target either has no form field error indicators, or at least one of the form field error indicators describes:

  • the cause of the error, or
  • how to resolve it,

in text that is included in the accessibility tree or included in the accessible name or accessible description of the test target.

Assumptions

There are currently no assumptions.

Accessibility Support

There are no major accessibility support issues known for this rule.

Background

Test Cases

Passed

Passed Example 1

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This input element has a form field error indicator that identifies it (by referencing its label), describes the cause of the error and how to resolve it.

<form>
	<label for="age">Age (years)</label>
	<input type="number" id="age" aria-describedby="error" value="0" />
	<span id="error">Invalid value for age. Age must be at least 1.</span><br />
	<input type="button" value="Submit" />
</form>

Passed Example 2

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This multiple input elements share a form field error indicator that identifies the elements unfilled (by referencing their labels), describes the cause of the error and how to resolve it.

<form>
	<h2 id="error">
		Name and color cannot be left unfilled. Please complete all required fields.
	</h2>
	<fieldset>
		<legend>Your data</legend>
		<label for="name">Name (required)</label>
		<input type="text" id="name" required />
		<br />
		<label for="address">Address</label>
		<input type="text" id="address" />
	</fieldset>
	<fieldset>
		<legend>Pick a color (required)</legend>
		<label><input type="radio" name="color" value="blue" required />Blue</label>
		<label><input type="radio" name="color" value="yellow" />Yellow</label>
	</fieldset>
	<input type="button" value="Submit" aria-describedby="error" />
</form>

Passed Example 3

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This input element does not have a form field error indicator.

<form>
	<label for="age">Age (years)</label>
	<input type="number" id="age" />
	<input type="button" value="Submit" />
</form>

Failed

Failed Example 1

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These multiple input elements share a form field error indicator but its message does not identify the elements that caused the error nor describes the cause of the error.

<form>
	<div id="error">Please fill the field correctly.</div>
	<label for="age">Age (years)</label>
	<input type="number" id="age" />
	<label for="name">Name</label>
	<input type="text" id="name" />
	<input type="button" value="Submit" />
</form>

Failed Example 2

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This input element has a form field error indicator but its message does not describe the cause of the error.

<form>
	<label for="age">Age (years)</label>
	<input type="number" id="age" />
	<span id="error">Please enter a correct age.</span><br />
	<input type="button" value="Submit" />
</form>

Failed Example 3

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This input element has a form field error indicator that identifies it (by referencing its label) and describes the cause of the error but the message is not visible.

<form>
	<label for="age">Age (years)</label>
	<input type="number" id="age" value="0" />
	<span id="error" style="display: none;">Invalid value for age. Age must be at least 1.</span><br />
	<input type="button" value="Submit" aria-describedby="error" />
</form>

Failed Example 4

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This input element has a form field error indicator that identifies it (by referencing its label) and describes the cause of the error but the message is not included in the accessibility tree.

<form>
	<label for="age">Age (years)</label>
	<input type="number" id="age" value="0" />
	<span id="error" aria-hidden="true">Invalid value for age. Age must be at least 1.</span><br />
	<input type="button" value="Submit" />
</form>

Failed Example 5

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These multiple input elements share a form field error indicator. The message describes the cause of the error but does not allow to identify the elements that caused the error because the same label is used in different fieldsets.

<form>
	<fieldset>
		<legend>Shipping</legend>
		<label for="shippingName">Name</label>
		<input type="text" id="shippingName" required />
		<label for="shippingAddress">Address</label>
		<input type="text" id="shippingAddress" required />
	</fieldset>
	<fieldset>
		<legend>Billing</legend>
		<label for="billingName">Name</label>
		<input type="text" id="billingName" />
		<label for="billingAddress">Address</label>
		<input type="text" id="billingAddress" />
	</fieldset>
	<span id="error">All required fields must be filled.<br />Please fill Name.<br />Please fill Address</span><br />
	<input type="button" value="Submit" />
</form>

Inapplicable

Inapplicable Example 1

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There are no elements with any of the required semantic roles.

<p>This is a paragraph.</p>

Glossary

Accessible Name

The accessible name is the programmatically determined name of a user interface element that is included in the accessibility tree.

The accessible name is calculated using the accessible name and description computation.

For native markup languages, such as HTML and SVG, additional information on how to calculate the accessible name can be found in HTML Accessibility API Mappings 1.0, Accessible Name and Description Computation (working draft) and SVG Accessibility API Mappings, Name and Description (working draft).

For more details, see examples of accessible name.

Note: As per the accessible name and description computation, each element always has an accessible name. When no accessible name is provided, the element will nonetheless be assigned an empty ("") one.

Note: As per the accessible name and description computation, accessible names are flat string trimmed of leading and trailing whitespace. Notably, it is not possible for a non-empty accessible name to be composed only of whitespace since these must be trimmed.

Accessibility Support for Accessible Name

  • Because the accessible name and description computation is not clear about which whitespace are considered, browsers behave differently when trimming and flattening the accessible name. For example, some browsers completely trim non-breaking spaces while some keep them in the accessible name.
  • There exists a popular browser which does not perform the same trimming and flattening depending whether the accessible name comes from content, an aria-label attribute, or an alt attribute.
  • There exists a popular browser which assign no accessible name (null) when none is provided, instead of assigned an empty accessible name ("").
  • The accessible name and description computation suggest that if an aria-labelledby attribute refers to an existing but empty element, the computation should stop and return an empty name without defaulting to the next steps. Several user agents and assistive technologies chose to use the next step in the computation in this case.

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.

Form Field Error Indicator

Any text, or non-text content, or an element that has presentation indicating that an error was identified which appears to be related to some user input into, or the lack of user input into some element. These could be different types of errors, for example:

  • missing input, for example a required form field that was left empty
  • incorrect input, such as an invalid password
  • input not in an expected format, expected range, or of an allowed value
  • timing error, such as session timeouts or expiration of an allowed action
  • authentication or authorization errors

Note: An error indicator can be a separate element in the page, but it can also be part of a form control. For example a red outline on a form control is often used to indicate an error. Not all red outlines are indicators of an error though. This depends on the presentation of the form control in relation to other elements on the page.

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
QualWebconsistentYesView Report

Acknowledgments

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