TAB ORDER GUIDELINES
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Table of Contents
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Overview
Not all users navigate the page with the mouse or a trackpad; some users only rely on keyboard to navigate. Many users with motor disabilities rely on a keyboard. Assistive technology users will also typically use a keyboard for navigation. In addition to traditional keyboards, some users may use a modified keyboard or other hardware that mimics the functionality of a keyboard.
Keyboard tab order allows keyboard users to properly navigate a web page. If tab order is implemented correctly a webpage will read similar to a book to a keyboard user. When done incorrectly a keyboard user may miss out or become confused with the order of the web page.
Ensure that when users navigate sequentially through content, they encounter information in a focus order that is consistent with the meaning of the content and can be operated from the keyboard.
Enable a user agent to provide an alternative presentation of content while preserving the reading order needed to understand the meaning.
Tab Order Guidelines
Keyboard accessibility is one of the most important aspects of web accessibility. Not all users navigate the page with the mouse or a trackpad; some users only rely on keyboard to navigate. Many users with motor disabilities rely on a keyboard. Assistive technology users will also typically use a keyboard for navigation. In addition to traditional keyboards, some users may use a modified keyboards keyboard or other hardware that mimics the functionality of a keyboard.
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Normal flow in the keyboard tab order will be broken when tabbing through the interactive elements.
If content is dynamically added in between of elements with positive tabindex, it will interfere with the normal flow of tabbing.
General Guidelines
The best practices for keyboard tab order should include the following:
Tab order should have a logical reading order, similar to a book. It should be from left to right and top to bottom.
As you are tabbing through a website, there must be a visible indication of where the tab focus is at.
When using the tabindex to adjust the tab order, use tabindex= "0" or tabindex= "-1" ONLY
Tabindex values of 1 or higher must NOT be used.
Example
The image below shows the correct reading order on a page that has multiple navigation links on the side panels.
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Please see more detailed information on how to comply with this guideline.
Focus Order Guidelines
Keyboard users should be able to navigate content in a correct order.
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Focusable components need to receive focus in an order that preserves meaning and operability only when navigation sequences affect meaning and operability.
In those cases where it is required, there may be more than one order that will preserve meaning and operability.
If there is more than one order that preserves meaning and operability, only one of them needs to be provided.
Please see more detailed information on how to comply with this guideline.
Provide Content In a Meaningful Sequence
Enable a user agent to provide an alternative presentation of content while preserving the reading order needed to understand the meaning.
It is important that it be possible to programmatically determine at least one sequence of the content that makes sense.
A sequence is meaningful if the order of content in the sequence cannot be changed without affecting its meaning. For example, if a page contains two independent articles, the relative order of the articles may not affect their meaning, as long as they are not interleaved. In such a situation, the articles themselves may have meaningful sequence, but the container that contains the articles may not have a meaningful sequence.
The semantics of some elements define whether or not their content is a meaningful sequence. For instance, in HTML, text is always a meaningful sequence. Tables and ordered lists are meaningful sequences, but unordered lists are not.
This helps people who rely on assistive technologies that read content aloud. The meaning evident in the sequencing of the information in the default presentation will be the same when the content is presented in spoken form.
Example 1:
In a multi-column document, the linear presentation of the content flows from the top of a column to the bottom of the column, then to the top of the next column.
Example 2:
CSS is used to position a navigation bar, the main story on a page, and a side story. The visual presentation of the sections does not match the programmatically determined order, but the meaning of the page does not depend on the order of the sections.
Example 3:
This example is to demonstrate how visual appearance may be enhanced via style sheets while still maintaining a meaningful presentation when style sheets are not applied. Using the positioning properties of CSS2, content may be displayed at any position on the user's viewport. Using structural elements ensures that the meaning of the content can still be determined when styling is not available.
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In this example structural markup (definition lists) have been applied to the content. CSS has been used to style the content into columnar form. Each class absolutely positions the content into columns and the margins have been set to 0 to override the default behavior of user agents to display HTML definition lists with the DD element indented.
Here is the content to be displayed:
| Code Block |
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<div class="box">
<dl>
<dt class="menu1">Products</dt>
<dd class="item1">Telephones</dd>
<dd class="item2">Computers</dd>
<dd class="item3">Portable MP3 Players</dd>
<dt class="menu2">Locations</dt>
<dd class="item4">Idaho</dd>
<dd class="item5">Wisconsin</dd>
</dt>
</dl>
</div>
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Here is the CSS which positions and styles the above elements:
| Code Block |
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.item1 {
left: 0;
margin: 0;
position: absolute;
top: 7em;
}
.item2 {
left: 0;
margin: 0;
position: absolute;
top: 8em;
}
.item3 {
left: 0;
margin: 0;
position: absolute;
top: 9em;
}
.item4 {
left: 14em;
margin: 0;
position: absolute;
top: 7em;
}
.item5 {
left: 14em;
margin: 0;
position: absolute;
top: 8em;
}
.menu1 {
background-color: #FFFFFF;
color: #FF0000;
font-family: sans-serif;
font-size: 120%;
left: 0;
margin: 0;
position: absolute;
top: 3em;
}
.menu2 {
background-color: #FFFFFF;
color: #FF0000;
font-family: sans-serif;
font-size: 120%;
left: 10em;
margin: 0;
position: absolute;
top: 3em;
}
#box {
left: 5em;
position: absolute;
top: 5em;
}
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When style sheets are applied, the data are displayed in two columns of "Products" and "Locations." When the style sheets are not applied, the text appears in a definition list which maintains the structure and reading order.