When tables are used to show data, the header cells that relate to the data cells need to be programatically linked. This makes table navigation for screen readers less painful.
Simple tables can have up to two levels of headings. One row of headers and/or one column of headings. A table with more than one row or more than one column of headings, is considered to be a complex table. Each table header cell should have
<th scope='col'> or
Note: Simple tables with headers in the first row and/or column don't actually need the scope attribute for assistive technology to read them correctly. However, 508 test procedures within the federal government require table headings to have either scope or id attributes.
Complex tables are tables with more than two levels of headers. Each header should be given a unique
id and each data cell should have a
headers attribute with each related header cell's id listed.
If a table has text associated with it, ensure the text is programatically linked to the table. This is usually with a
<caption> element. This element should be the first element under the
<table> element. While a
caption is not required, it can be very helpful to screen reader users navigating the page. A
caption element is strongly encouraged on data tables as it gives context to the data.
- Identify 'data' tables (layout tables are exempt).
- View the table source code.
- Identify the table headers.
- Check for scope on simple tables.
- Check for id and headers on complex tables.
<table> <caption>User's Height and Weight</caption> <tr> <th scope='col'> Name </th> <th scope='col'> Height </th> <th scope='col'> Age </th> </tr> <tr> <th scope='row'> Walter </th> <td>6'4</td> <td>34</td> </tr> <tr> <th scope='row'> Steve </th> <td>5'4</td> <td>30</td> </tr> </table>
Looking at this table, the column headers all relate to the cells below. This is done programatically with
scope='col'. Each height and age value is related to the person and this is done programatically with
<table> <caption>User's Height and Weight</caption> <tr> <th rowspan='2' id='name'> Name </th> <th colspan='2' id='height'> Height </th> <th rowspan='2' id='age'> Age </th> </tr> <tr> <th id='feet' headers='height'> Feet </th> <th id='inches' headers='height'> Inches </th> </tr> <tr> <th headers='name' id='walter'> Walter </th> <td headers='height feet walter'>6</td> <td headers='height inches walter'>4</td> <td headers='age walter'>34</td> </tr> <tr> <th headers='name' id='steve'> Steve </th> <td headers='height feet steve'>5</td> <td headers='height inches steve'>4</td> <td headers='age steve'>30</td> </tr> </table>
This is an example of a complex table, all the cells are associated to their respective headers with the
headersattribute. Most tables don't require this level of complexity.