AccessiWeb 2.2 - Rule 1.3.1

Summary

This test consists in checking the relevancy of the alternative of each img that handles any information.

Business description

Criterion : 1.3

Test : 1.3.1

Test description :

For each image that conveys information (img tag) with an alt attribute, is the content of this attribute relevant (except in special cases)?

Level : Bronze

Technical description

Scope : page

Decision level :decidable

Algorithm

Selection

Set1 (img tags identified as an informative image from html markers)

All the img tags not within an a tag (in this case, the image would be considered as a link) with an alt attribute and with an id attribute or a class attribute or a role that matches one of the values set by the user through the "INFORMATIVE_IMAGE_MARKER" parameter. The elements of Set2 with a longdesc attribute are added to that collection.

Set2 (img tags not identified as an informative image from html markers)

All the img tags not within an a tag with an alt attribute, without a longdesc attribute that don't have an id attribute or a class attribute or a role that matches one the values set by the use through the "DECORATIVE_IMAGE_MARKER" parameter or the "INFORMATIVE_IMAGE_MARKER" parameter. That means select all the img tags not within an a tag with an alt attribute of the page when these parameters are empty.

Process

Test1

For each element of Set1 (informative img identified by a html marker), check the relevancy of the content of the alt attribute (not empty, different from the value of the src attribute and without image extension such as jpg, jpeg, bmp, png, tiff). For each element returning false in Test1, raise a MessageA For each element returning true in Test1, raise a MessageB

Test2

For each element of Set2 (img tags not identified as informative image), check the relevancy of the content of the alt attribute (not empty, different from the value of the src attribute and without image extension such as jpg, jpeg, bmp, png, tiff). For each element returning false in Test3, raise a MessageC For each element returning true in Test4, raise a MessageD

MessageA : Informative image with not pertinent alternative
  • code : NotPertinentAlt
  • status: Failed
  • parameter : alt attribute, src attribute, Snippet
  • present in source : yes
MessageB : Check the pertinence of the informative image
  • code : CheckPertinenceOfAltAttributeOfInformativeImage
  • status: Pre-qualified
  • parameter : alt attribute, src attribute, Snippet
  • present in source : yes
MessageC : Check the nature of the image with a not pertinent alternative
  • code : CheckNatureOfImageWithNotPertinentAlt
  • status: Pre-qualified
  • parameter : alt attribute, src attribute, Snippet
  • present in source : yes
MessageC : Check the nature of the image and the pertinence of its alternative
  • code : CheckNatureOfImageAndAltPertinence
  • status: Pre-qualified
  • parameter : alt attribute, src attribute, Snippet
  • present in source : yes

Analysis

Not Applicable

Set1 and Set2 are empty (The page has no img tag)

Failed

Test1 returns false for at least one element (one img identified as informative has a not pertinent alternative)

Pre-Qualified

In all other cases