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 above on level A and above.
      • 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).

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 ("").

Examples for Accessible Name

Note: The examples presented here are non-normative and not testable. They serve to illustrate some common pitfalls about the definition and to help implementers of ACT rules understand it.

The input elements have an accessible name of, respectively, "Billing Name" and "Billing Address". These accessible names are given by the aria-labelledby attributes and associated elements.

<div id="myBillingId">Billing</div>

<div>
	<div id="myNameId">Name</div>
	<input type="text" aria-labelledby="myBillingId myNameId" />
</div>
<div>
	<div id="myAddressId">Address</div>
	<input type="text" aria-labelledby="myBillingId myAddressId" />
</div>

This button element has an accessible name of "Share ACT rules" given by its aria-label attribute.

<button aria-label="Share ACT rules">Share</button>

This img element has an accessible name of "ACT rules" given by its alt attribute.

<img src="#" alt="ACT rules" />

The button element has an accessible name of "Share ACT rules" given by the enclosing label element (implicit label)

<label>Share ACT rules<button>Share</button></label>

The button element has an accessible name of "Share ACT rules" given by the associated label element (explicit label)

<label for="act-rules">Share ACT rules</label><button id="act-rules"></button>

This a element has an accessible name of "ACT rules" given from its content. Note that not all semantic roles allow name from content.

<a href="https://act-rules.github.io/">ACT rules</a>

This span element has an empty accessible name ("") because span does not allow name from content.

<span>ACT rules</span>

This span element has an empty accessible name ("") because span is not a labelable element.

<label>ACT rules<span></span></label>

Note: When the same element can have an accessible name from several sources, the order of precedence is: aria-labelledby, aria-label, own attributes, label element, name from content. The examples here are listed in the same order.

Note: For more examples of accessible name computation, including many tricky cases, check the Accessible Name Testable Statements.

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.

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).

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 with using sequential keyboard navigation regardless of the assistive technologies used, even though the element would not be included in the accessibility tree.

Examples for Included in the accessibility tree

Note: The examples presented here are non-normative and not testable. They serve to illustrate some common pitfalls about the definition and to help implementers of ACT rules understand it.

This span element is included in the accessibility tree (by default, elements are included in the accessibility tree).

<span>ACT rules</span>

This span element is not included in the accessibility tree because it is hidden to everybody by the CSS property.

<span style="display:none">ACT rules</span>

This span element is not included in the accessibility tree because it is explicitly removed by the aria-hidden attribute.

<span aria-hidden="true">ACT rules</span>

This span element is positioned off screen, hence is not visible, but is nonetheless included in the accessibility tree.

<span style="position: absolute; top:-9999em">ACT rules</span>

Although the span element with an id of "label" is not itself included in the accessibility tree, it still provides an accessible name to the other span, via the aria-labelledby attribute. Thus, it is still indirectly exposed to users of assistive technologies. Removing an element from the accessibility tree is not enough to remove all accessibility concerns from it since it can still be indirectly exposed.

<span id="label" style="display:none">ACT rules</span>
<span aria-labelledby="label">Accessibility Conformance Testing rules</span>

Although this input element is not included in the accessibility tree, it is still focusable, hence users of assistive technologies can still interact with it by sequential keyboard navigation. This may result in confusing situations for such users (and is in direct violation of the fourth rule of ARIA (working draft)).

<input type="text" aria-hidden="true" name="fname" />

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.

Examples for Visible

Note: The examples presented here are non-normative and not testable. They serve to illustrate some common pitfalls about the definition and to help the implementers of ACT rules understand it.

This span element is visible (by default, elements are visible).

<span>Now you can see me!</span>

This span element is not visible because of the CSS visibility property.

<span style="visibility: hidden">I'm the invisible man</span>

This span element is not visible because of the CSS display property.

<span style="display: none">I'm the invisible man</span>

This span element is not visible because it is positioned off-screen

<span style="position: absolute; top: -9999px; left: -9999px;">Incredible how you can</span>

This span element is not visible because it contains only whitespace and line breaks.

<span>
	<br />
	&nbsp;
</span>

This span element is not visible because it has the exact same color as its background.

<span style="color: #00F; background: #00F;">See right through me</span>

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.

ToolConsitencyCompleteReport
QualWebconsistentYesView Report

Acknowledgments

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