Server-side image maps must not be used

Rule ID: server-side-image-map
Ruleset: axe-core 4.2
User Impact: Minor
Guidelines: WCAG 2.1 (A), WCAG 2.0 (A), Section 508

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Compliance Data & Impact

User Impact

Minor
▼
Minor
Critical

Disabilities Affected

  • Blind
  • Deafblind
  • Mobility

Standard(s)

  • WCAG 2.1 (A)
  • WCAG 2.0 (A)
  • Section 508

WCAG Success Criteria [WCAG 2.1 (A)]

  • 2.1.1: MUST: Keyboard

WCAG Success Criteria [WCAG 2.0 (A)]

  • 2.1.1: MUST: Keyboard

Section 508 Guidelines

  • 1194.22: MUST: Web based intranet and Internet Information & Applications
  • 1194.22 (f): MUST: Client-side image maps shall be provided instead of server-side image maps except where the regions cannot be defined with an available geometric shape.

How to Fix the Problem

Change all server-side image maps to client-side image maps.

Bad Example

Don't use server-side image maps.

<a href="/maps/nav.map"><img src="/images/navbar.gif" ismap></a>

Good Example

A client-side image map is contained by an <img> element. They have a usemap attribute containing the name of the image map (i.e. <img usemap="myImageMap" src="..." >). After the <img> element, a set of <map> elements encloses the space where clickable hotspots are defined on the map as follows: 

<img src="images/solar_system.jpg" alt="Solar System" width="472" height="800" usemap="#Map"/>
<map name="Map">
    <area shape="rect" coords="115,158,276,192" href="http://en.wikipedia.org/wiki/Mercury_%28planet%29" alt="Mercury">
    <area shape="rect" coords="115,193,276,234" href="http://en.wikipedia.org/wiki/Venus" alt="Venus">
    Remaining hotspots in image map...
</map>

Why it Matters

Server-side image maps are not keyboard accessible; mouse clicks are required to access the links contained in the image, making the image inaccessible to people who only use keyboards for their navigation.

Server side image maps pass the coordinates of the mouse click to the server-side script used to process the image map. Because they rely on mouse clicks, they are not keyboard accessible, whereas client-side image maps are keyboard accessible. Further, it is not possible to provide text alternatives to the actionable areas of a server-side image map like you can with the areas of a client-side image map.

Rule Description

The document contains an image map that is server-side instead of client-side.

The Algorithm (in simple terms)

Ensures that server-side image maps are never used.

Resources

Deque University Course Pages (subscription required)

Contribute to axe-core on GitHub

Other Resources

You may also want to check out these other resources.

Refer to the complete list of axe 4.2 rules.

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