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Audit bypass

Ensure each page has at least one mechanism for a user to bypass navigation and jump straight to the content

Impact:

Serious

WCAG-Konformität:

A
WCAG 2.4.1

Issue type:

needs review

Bypass Blocks of Repeated Content

This rule checks that each page has a mechanism to bypass repeated blocks of content.

Applicability

This rule applies to any HTML web page.

Expectation

For each test target, the outcome of at least one of the following rules is passed:

Background

The instruments used to pass this rule (if any), must meet all level A Success Criteria in order to fully satisfy Success Criterion 2.4.1 Bypass Block. These extra requirements are left out of this rule, and should be tested separately.

Assumptions

This rule assumes that the mean to bypass blocks is included in the content of the HTML web page. For example, server-side scripting, or a global "settings" page, can provide a functionality similar to Block of repeated content is collapsible by serving a modified version of the page; in which case this rule would fail but Success Criterion 2.4.1 Bypass blocks could nonetheless be satisfied.
This rule assumes that frame and frameset elements are not used, given that they are deprecated in HTML5. They can be used to organize content as per H70: Using frame elements to group blocks of repeated material and H64: Using the title attribute of the frame and iframe elements, in that case, this rule would fail but Success Criterion 2.4.1 Bypass blocks could nonetheless be satisfied.
This rule assumes that completely removing blocks of repeated content is sufficient to pass Success Criterion 2.4.1 Bypass blocks. However, providing an instrument to remove them without providing one to show them again is likely going to create other unrelated issues.
This rule assumes that repeated content that is at the end of the page (and not followed any non-repeated content) can be bypassed by means provided by user agents (such as pressing the "End" key to scroll to the bottom of the page). Therefore, they do not need any other way of being bypassed and are ignored by this rule. If there isn't a way to bypass them, this rule may pass while Success Criterion 2.4.1 Bypass blocks is not satisfied.
This rule assumes that the language of each test target can be correctly determined (either programmatically or by analyzing the content), and sufficiently understood.

Accessibility Support

Techniques and solutions that identify blocks of content are sufficient ways of passing Success Criterion 2.4.1 Bypass blocks. They are, however, only beneficial for users who have ways of navigating with this information. For example, adding headings to a document will only help users who can "jump" from heading to heading (such a possibility can be provided by browsers, browsers plugins, screen readers, or other assistive technologies). Techniques and solutions based on links will benefit all users (for example, sighted keyboard users with no other assistive technology) and are therefore recommended.

If the instruments used to pass some of the atomic rules are not keyboard accessible, or not included in the accessibility tree, passing this rule can still leave many users without a way to bypass blocks of repeated content. WCAG's definition of mechanism has a note saying that it "needs to meet all success criteria for the conformance level claimed". This includes Success Criterion 2.1.1 Keyboard and Success Criterion 4.1.2 Name, Role, Value which are both at level A.

This rule only checks if there is a way to bypass at least one section of repeated content. On pages with several interleaved repeated and non-repeated content, this is not sufficient to satisfy Success Criterion 2.4.1 Bypass blocks. Checking for more sections to bypass was considered but rejected due to both the added complexity it would create, and the risk of failing on pages that might be correct.

Bibliography

Understanding Success Criterion 2.4.1: Bypass Blocks
Creating links to skip blocks of content:
- Technique G1: Adding a link at the top of each page that goes directly to the main content area
- Technique G123: Adding a link at the beginning of a block of repeated content to go to the end of the block
- Technique G124: Adding links at the top of the page to each area of the content
Grouping and identifying blocks of content:

To avoid using landmarks for the non-repeated content, which would satisfy Success Criterion 2.4.1 Bypass Block, this rule uses <div id="main"> in its test cases to indicate where non-repeating content exists. It is recommended to use the main landmark instead. The aside and nav elements are each a block of repeated content due to the link inside the nav element to a page with similar blocks of content.

Test Cases

Passed

Passed Example 1

This HTML web page is passing rule Block of repeated content is collapsible.

<html>
	<head>
		<script src="/test-assets/bypass-blocks-cf77f2/toggle-display.js"></script>
		<title>The Three Kingdoms, Chapter 1</title>
	</head>
	<body>
		<a href="#" onclick="toggleHidden('chapters-navigation')">Toggle table of content</a>

		<nav id="chapters-navigation">
			<ol>
				<li><a>Chapter 1</a></li>
				<li><a href="/test-assets/bypass-blocks-cf77f2/chapter2.html">Chapter 2</a></li>
			</ol>
		</nav>

		<div id="main">
			<p>
				Unity succeeds division and division follows unity. One is bound to be replaced by the other after a long span
				of time.
			</p>
		</div>
	</body>
</html>

Passed Example 2

This HTML web page is passing rule Document has heading for non-repeated content.

<html>
	<head>
		<title>The Three Kingdoms, Chapter 1</title>
	</head>
	<body>
		<nav id="chapters-navigation">
			<ol>
				<li><a>Chapter 1</a></li>
				<li><a href="/test-assets/bypass-blocks-cf77f2/chapter2.html">Chapter 2</a></li>
			</ol>
		</nav>

		<div id="main">
			<h1>Three Heroes Swear Brotherhood at a Feast in the Peach Garden</h1>
			<p>
				Unity succeeds division and division follows unity. One is bound to be replaced by the other after a long span
				of time.
			</p>
		</div>
	</body>
</html>

Passed Example 3

This HTML web page is passing rule Document has a landmark with non-repeated content.

<html>
	<head>
		<title>The Three Kingdoms, Chapter 1</title>
	</head>
	<body>
		<nav id="chapters-navigation">
			<ol>
				<li><a>Chapter 1</a></li>
				<li><a href="/test-assets/bypass-blocks-cf77f2/chapter2.html">Chapter 2</a></li>
			</ol>
		</nav>

		<main>
			<p>
				Unity succeeds division and division follows unity. One is bound to be replaced by the other after a long span
				of time.
			</p>
		</main>
	</body>
</html>

Passed Example 4

This HTML web page is passing rule Document has an instrument to move focus to non-repeated content.

<html lang="en">
	<head>
		<title>The Three Kingdoms, Chapter 1</title>
	</head>
	<body>
		<a href="#main">Skip to main content</a>
		<a href="/test-assets/bypass-blocks-cf77f2/chapter2.html">Read Chapter 2</a>

		<aside id="about-book">
			<p>The Romance of the Three Kingdoms is a 14th century historical novel.</p>
		</aside>

		<div id="main">
			<p>
				Unity succeeds division and division follows unity. One is bound to be replaced by the other after a long span
				of time.
			</p>
		</div>
	</body>
</html>

Passed Example 5

This HTML web page is passing rule Document has an instrument to move focus to non-repeated content.

<html lang="en">
	<head>
		<title>The Three Kingdoms, Chapter 1</title>
	</head>
	<body>
		<nav id="local-navigation">
			<a href="#bio-translator">Skip to translator's biography</a>
			<a href="#about-book">Skip to information about the book</a>
			<a href="#main">Skip to main content</a>
		</nav>

		<aside id="bio-translator">
			<p>Yu Sumei is a professor of English at East China Normal University.</p>
		</aside>
		<aside id="about-book">
			<p>The Romance of the Three Kingdoms is a 14th century historical novel.</p>
		</aside>

		<div id="main">
			<p>
				Unity succeeds division and division follows unity. One is bound to be replaced by the other after a long span
				of time.
			</p>
			<a href="/test-assets/bypass-blocks-cf77f2/chapter2.html">Read Chapter 2</a>
		</div>
	</body>
</html>

Passed Example 6

This HTML web page is passing rule Document has an instrument to move focus to non-repeated content.

<html lang="en">
	<head>
		<title>The Three Kingdoms, Chapter 1</title>
	</head>
	<body>
		<aside id="bio-translator">
			<a href="#about-book">Skip to information about the book</a>
			<p>Yu Sumei is a professor of English at East China Normal University.</p>
		</aside>
		<aside id="about-book">
			<a href="#main">Skip to main content</a>
			<p>The Romance of the Three Kingdoms is a 14th century historical novel.</p>
		</aside>

		<div id="main">
			<p>
				Unity succeeds division and division follows unity. One is bound to be replaced by the other after a long span
				of time.
			</p>
			<a href="/test-assets/bypass-blocks-cf77f2/chapter2.html">Read Chapter 2</a>
		</div>
	</body>
</html>

Passed Example 7

This HTML web page is passing rule Block of repeated content is collapsible because it has no block of repeated content before non-repeated perceivable content. Note that this does not pass Technique SCR28: Using an expandable and collapsible menu to bypass block of content because the block of repeated content which is after the non-repeated content cannot be toggled.

<html lang="en">
	<head>
		<title>The Three Kingdoms, Chapter 1</title>
	</head>
	<body>
		<div id="main">
			<p>
				Unity succeeds division and division follows unity. One is bound to be replaced by the other after a long span
				of time.
			</p>
		</div>

		<a href="/test-assets/bypass-blocks-cf77f2/chapter2.html">Read Chapter 2</a>

		<aside id="about-book">
			The Romance of the Three Kingdoms is a 14th century historical novel.
		</aside>
	</body>
</html>

Passed Example 8

This HTML web page is passing rule Document has an instrument to move focus to non-repeated content because the button is such an instrument. Note that it does not pass Technique G1: Adding a link at the top of each page that goes directly to the main content area nor Technique G123: Adding a link at the beginning of a block of repeated content to go to the end of the block because the instrument is a button, not a link.

<html lang="en">
	<head>
		<title>The Three Kingdoms, Chapter 1</title>
	</head>
	<body>
		<button onclick="location.assign('#main')">Skip to main content</button>

		<aside id="about-book">
			<p>The Romance of the Three Kingdoms is a 14th century historical novel.</p>
		</aside>

		<div id="main">
			<p>
				Unity succeeds division and division follows unity. One is bound to be replaced by the other after a long span
				of time.
			</p>
			<a href="/test-assets/bypass-blocks-cf77f2/chapter2.html">Read Chapter 2</a>
		</div>
	</body>
</html>

Passed Example 9

This HTML web page is passing rule Document has an instrument to move focus to non-repeated content because the link with target #brewitt-taylor moves focus just before some non-repeated content after repeated content. Note that it does not necessarily pass Technique G124: Adding links at the top of the page to each area of the content because the <div id="main"> element is arguably a single "area of the content", and the technique requires only one link per such area.

<html>
	<head>
		<title>Comparing translations of the Romance of the Three Kingdoms, Chapter one</title>
	</head>
	<body>
		<nav id="local-navigation">
			<a href="#local-navigation">Skip to local navigation</a>
			<a href="#brewitt-taylor">Skip to Brewitt-Taylor's translation</a>
			<a href="#roberts">Skip to Roberts' translation</a>
			<a href="#yu">Skip to Yu's translation</a>
			<a href="#about-book">Skip to information about the book</a>
		</nav>

		<aside id="about-book">
			<p>The Romance of the Three Kingdoms is a 14th century historical novel.</p>
		</aside>

		<div id="main">
			<p id="brewitt-taylor">
				Three Heroes Swear Brotherhood in the Peach Garden (Translation by Charles Henry Brewitt-Taylor)
			</p>
			<p>
				The world under heaven, after a long period of division, tends to unite; after a long period of union, tends to
				divide.
			</p>

			<p id="roberts">Three Bold Spirits Plight Mutual Faith in the Peach Garden (Translation by Moss Roberts)</p>
			<p>The empire, long divided, must unite; long united, must divide. Thus it has ever been.</p>

			<p id="yu">Three Heroes Swear Brotherhood at a Feast in the Peach Garden (Translation by Yu Sumei)</p>
			<p>
				Unity succeeds division and division follows unity. One is bound to be replaced by the other after a long span
				of time.
			</p>
			<a href="/test-assets/bypass-blocks-cf77f2/chapter2.html">Read Chapter 2</a>
		</div>
	</body>
</html>

Passed Example 10

This HTML web page is passing rule Document has an instrument to move focus to non-repeated content. Note that it does not necessarily pass Technique G124: Adding links at the top of the page to each area of the content because the both the nav and aside elements are arguably different "areas of the content", and the technique requires exactly one link per such area.

<html lang="en">
	<head>
		<title>The Three Kingdoms, Chapter 1</title>
	</head>
	<body>
		<nav id="local-navigation">
			<a href="#local-navigation">Skip to local navigation</a>
			<a href="#main">Skip to main content</a>
		</nav>

		<aside id="about-book">
			<p>The Romance of the Three Kingdoms is a 14th century historical novel.</p>
		</aside>

		<div id="main">
			<p>
				Unity succeeds division and division follows unity. One is bound to be replaced by the other after a long span
				of time.
			</p>
			<a href="/test-assets/bypass-blocks-cf77f2/chapter2.html">Read Chapter 2</a>
		</div>
	</body>
</html>

Passed Example 11

This HTML web page is passing rule Block of repeated content is collapsible. Note that it does not pass Technique SCR28: Using an expandable and collapsible menu to bypass block of content because the technique requires that the blocks can be toggled on and off, but here they can only be removed.

<html>
	<head>
		<script src="/test-assets/bypass-blocks-cf77f2/toggle-display.js"></script>
		<title>The Three Kingdoms, Chapter 1</title>
	</head>
	<body>
		<button onclick="hide('chapters-navigation')">Hide table of content</button>

		<nav id="chapters-navigation">
			<ol>
				<li><a>Chapter 1</a></li>
				<li><a href="/test-assets/bypass-blocks-cf77f2/chapter2.html">Chapter 2</a></li>
			</ol>
		</nav>

		<div id="main">
			<p>
				Unity succeeds division and division follows unity. One is bound to be replaced by the other after a long span
				of time.
			</p>
		</div>
	</body>
</html>

Passed Example 12

This HTML web page is passing rule Document has an instrument to move focus to non-repeated content because the second link is such an instrument. Note that it does not pass Technique G1: Adding a link at the top of each page that goes directly to the main content area because the skip link is not the first focusable element on the page.

<html lang="en">
	<head>
		<title>The Three Kingdoms, Chapter 1</title>
	</head>
	<body>
		<a href="https://act-rules.github.io/">ACT rules</a>
		<a href="#main">Skip to main content</a>
		<a href="/test-assets/bypass-blocks-cf77f2/chapter2.html">Read Chapter 2</a>

		<aside id="about-book">
			<p>The Romance of the Three Kingdoms is a 14th century historical novel.</p>
		</aside>

		<div id="main">
			<p>
				Unity succeeds division and division follows unity. One is bound to be replaced by the other after a long span
				of time.
			</p>
		</div>
	</body>
</html>

Failed

Failed Example 1

This HTML web page does not pass any of the input rules.

<html lang="en">
	<head>
		<title>The Three Kingdoms, Chapter 1</title>
	</head>
	<body>
		<a href="/test-assets/bypass-blocks-cf77f2/chapter2.html">Read Chapter 2</a>

		<aside id="about-book">
			The Romance of the Three Kingdoms is a 14th century historical novel.
		</aside>

		<div id="main">
			<strong style="font-size: 18pt">Three Heroes Swear Brotherhood at a Feast in the Peach Garden</strong>
			<p>
				Unity succeeds division and division follows unity. One is bound to be replaced by the other after a long span
				of time.
			</p>
		</div>
	</body>
</html>

Inapplicable

Inapplicable Example 1

This document is not an HTML web page.

<svg xmlns="http://www.w3.org/2000/svg">
  <title>This is an SVG</title>
</svg>

Autoren: Jean-Yves Moyen

Finanzierung: WAI-Tools

Assets:

_Romance of the Three Kingdoms_ by Luo Guanzhong, translation by Charles Henry Brewitt-Taylor (Tuttle Publishing, 1925, ISBN 9780804834674)
_Three Kingdoms_ by Luo Guanzhong, translation by Moss Roberts (Foreign Language Press, 1976, ISBN 7-119-00590-1)
_The Three Kingdoms_ by Luo Guanzhong, translation by Yu Sumei (Tuttle publishing, 2014, ISBN 9780804843935)