Rule 1.2.1

Summary

This test consists in checking whether the alt attribute of each decorative image is empty.

Business description

Criterion

1.2

Test

1.2.1

Description

Chaque image de décoration sans légende (balise img) et ayant un attribut alt vérifie-t-elle ces conditions :

  • le contenu de l'attribut alt est vide (alt="")
  • l'image de décoration ne possède pas d'attribut title

Level

A

Technical description

Scope

Page

Decision level

Semi-Decidable

Algorithm

Selection

Set1

All the <img> tags of the page not within a link, without <longdesc> attribute and not identified as captcha (see Notes about captcha detection) (css selector : img:not(a img):not([longdesc]))

Set2

All the elements of Set1 identified as decorative 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 (decorative <img> identified by a html marker), check that the content of the "alt" attribute is empty.

For each element returning false in Test1, raise a MessageA.

Test2

For each element of Set2 (decorative <img> identified by a html marker), check that the "title" attribute is missing.

For each element returning false in Test2, raise a MessageB.

Test3

For each element of Set3 (<img> tags not identified as decorative image), check that the content of the "alt" attribute empty.

For each element returning false in Test3, raise a MessageC. For each element returning true in Test3, raise a MessageD.

Test4

For each element of Set3 (decorative <img> identified by a html marker), check that the "title" attribute is missing.

For each element returning false in Test4, raise a MessageC. For each element returning true in Test4, raise a MessageD.

Messages

MessageA : Decorative image with not empty alternative
  • code : DecorativeElementWithNotEmptyAltAttribute
  • status: Failed
  • parameter : "alt" attribute, "title" attribute, "src" attribute, Snippet
  • present in source : yes
MessageB : Decorative image with a title attribute
  • code : DecorativeElementWithTitleAttribute
  • status: Failed
  • parameter : "alt" attribute, "title" attribute, "src" attribute, Snippet
  • present in source : yes
MessageC : Check the nature of the image with a not empty alternative
  • code : CheckNatureOfElementWithNotEmptyAltAttribute
  • status: Pre-qualified
  • parameter : Snippet
  • present in source : yes
MessageD : Check the nature of the image with a empty alternative
  • code : CheckNatureOfElementWithEmptyAltAttribute
  • status: Pre-qualified
  • parameter : Snippet
  • present in source : yes

Analysis

Not Applicable

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

Failed

At least one <img> identified as decorative has a not empty alternative (Test1 OR Test2 returns false for at least one element)

Passed

All the <img> of the page are identified as decorative and have an empty alternative (Set3 is empty and Test1 AND Test2 returns true for all element)

Pre-qualified

In all other cases

Notes

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