Rule 1.3.2

Summary

This test consists in checking whether the alt attribute of each clickable area that convey information is pertinent.

Business description

Criterion

1.3

Test

1.3.2

Description

Chaque zone (balise area) d'une image réactive, porteuse d'information et ayant un attribut alt, vérifie-t-elle ces conditions (hors cas particuliers) ?

  • Le contenu de l'attribut alt est pertinent
  • S'il est présent, le contenu de l'attribut title est identique au contenu de l'attribut alt

Level

A

Technical description

Scope

Page

Decision level

Decidable

Algorithm

Selection

Set1

All the <area> tags, defined within a <map> tag whose the "id" attribute corresponds to the "usemap" attribute of an <img> tag, with a "href" and an "alt" attribute

Set2

All the elements of Set1 identified as informative image by marker usage (see Notes for details about detection through marker)

Set3

All the elements of Set1 identified neither as informative image, nor as decorative image by marker usage (see Notes for details about detection through marker)

Process

Tests

Test1

For each element of Set2, check whether the content of the "alt" attribute is not relevant (see Notes for details about relevancy test).

For each occurrence of true-result of Test1, raise a MessageA.

For each occurrence of false-result of Test1, raise a MessageB.

Test2

For each element of Set2, check whether the content of the "alt" attribute is identical to the content of the "title" attribute.

For each occurrence of false-result of Test2, raise a MessageC.

Test3

For each element of Set2, check whether the content of the "alt" attribute is not relevant (see Notes for details about relevancy test).

For each occurrence of true-result of Test3, raise a MessageD.

For each occurrence of false-result of Test3, raise a MessageE.

Test4

For each element of Set2, check whether the content of the "alt" attribute is identical to the content of the "title" attribute.

For each occurrence of false-result of Test4, raise a MessageD.

Messages

MessageA
  • code : NotPertinentAlt
  • status: Failed
  • parameter : "alt" attribute, "title" attribute, "href" attribute, tag name
  • present in source : yes
MessageB
  • code : CheckPertinenceOfAltAttributeOfInformativeImage
  • status: Pre-Qualified
  • parameter : "alt" attribute, "title" attribute, "href" attribute, tag name
  • present in source : yes
MessageC
  • code : TitleNotIdenticalToAlt
  • status: Pre-Qualified
  • parameter : "alt" attribute, "title" attribute, "href" attribute, tag name
  • present in source : yes
MessageD
  • code : CheckNatureOfImageWithNotPertinentAlt
  • status: Pre-Qualified
  • parameter : "alt" attribute, "title" attribute, "href" attribute, tag name
  • present in source : yes
MessageE
  • code : CheckNatureOfImageAndAltPertinence
  • status: Pre-Qualified
  • parameter : "alt" attribute, "title" attribute, "href" attribute, tag name
  • present in source : yes

Analysis

Failed

At least one <area> tag identified as informative has an irrelevant "alt" attribute (Test1 returns true for at least one element)

Pre-qualified

The alternatives of all the <area> tags need to be manually checked (Test1 returns false for all the elements of Set1)

Not Applicable

The page has no <area> tag with an "alt" attribute (Set1 is empty)

Markers

Informative images markers are set through the INFORMATIVE_IMAGE_MARKER parameter.

Decorative images markers are set through the DECORATIVE_IMAGE_MARKER parameter.

The value(s) passed as marker(s) will be checked against the following attributes:

  • class
  • id
  • role

Captcha detection

An element is identified as a CAPTCHA when the "captcha" occurrence is found :

  • on one attribute of the element
  • or within the text of the element
  • or on one attribute of one parent of the element
  • or within the text of one parent of the element
  • or on one attribute of a sibling of the element
  • or within the text of a sibling of the element

Alt attribute relevancy

The content of the "alt" attribute is seen as not relevant if :

  • empty
  • only composed of non-alphanumerical characters
  • identical to the "src" attribute
  • it has an extension of image type (loaded by the nomenclature named ImageFileExtensions composed of : jpg, gif, jpeg, png, bmp)