Techniques for WCAG 2.0

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F58: Failure of Success Criterion 2.2.1 due to using server-side techniques to automatically redirect pages after a time-out

Important Information about Techniques

See Understanding Techniques for WCAG Success Criteria for important information about the usage of these informative techniques and how they relate to the normative WCAG 2.0 success criteria. The Applicability section explains the scope of the technique, and the presence of techniques for a specific technology does not imply that the technology can be used in all situations to create content that meets WCAG 2.0.

Applicability

This failure relates to:

User Agent and Assistive Technology Support Notes

See User Agent Support Notes for F58.

Description

Server-side scripting languages allow developers to set the non-standard HTTP header "Refresh" with a time-out (in seconds) and a URI to which the browser is redirected after the specified time-out. If the time interval is too short, people who are blind will not have enough time to make their screen readers read the page before the page refreshes unexpectedly and causes the screen reader to begin reading at the top. Sighted users may also be disoriented by the unexpected refresh.

The HTTP header that is set is Refresh: {time in seconds}; url={URI of new location}. It is also possible to omit the URI and obtain a periodically refreshing page, which causes the same problem. The HTTP header that is set is Refresh: {time in seconds}.

Examples

Failure Example 1

The following example is a failure because a timed server-side redirect is implemented in Java Servlets or JavaServer Pages (JSP).

Example Code:


public void doGet (HttpServletRequest request, HttpServletResponse response)
      throws IOException, ServletException {
        response.setContentType("text/html");
	PrintWriter out = response.getWriter();
	response.setHeader("Refresh", "10; URL=TargetPage.html");
	out.println("<!DOCTYPE html PUBLIC \"-//W3C//DTD XHTML 1.0 Transitional//EN\"
	 \"http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd\">");
	out.println("<html><head><title>Redirect</title></head><body>");
	out.println("<p>This page will redirect you in 10 seconds.</p>");
	out.println("</body></html>");
  }

Failure Example 2

The following example is a failure because a timed server-side redirect is implemented in Active Server Pages (ASP) with VBScript.

Example Code:


 <% @Language = "VBScript" %>
 <% option explicit 
 Response.Clear
 Response.AddHeader "Refresh", "5; URL=TargetPage.htm"
 %><!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Strict//EN" 
 "http://www.w3.org/TR/xhtml1/DTD/xhtml1-strict.dtd">
 <html xmlns="http://www.w3.org/1999/xhtml" lang="en" xml:lang="en">
 …
 <!--HTML code for content that is shown before the redirect is triggered-->
 

Resources

Resources are for information purposes only, no endorsement implied.

Tests

Procedure

  1. When a Web page is rendered, check to see if it automatically redirects to another page after some period of time without the user taking any action.

Expected Results