alt="" is treated as valid alt text

[adamraine]

Product

axe-core

Product Version

4.10.2

Latest Version

• I have tested the issue with the latest version of the product

Issue Description

Expectation

I expected axe to flag image elements which have alt=""

Actual

Axe does not flag image elements with alt=""

How to Reproduce

Generate an axe report of https://thelibre.news/would-you-pay-for-free-software/

Several images don't have any real alt text if you do the query document.querySelectorAll('img[alt=""]'), but axe does not flag them.

Additional context

GoogleChrome/lighthouse#16346

[WilcoFiers]

Thank you for reporting this issue. I understand your expectation that axe should flag images with alt="", but I want to explain why this is working as intended. In HTML, alt="" explicitly indicates that the image is decorative and should be ignored by screen readers, which is the correct way to mark decorative images according to WCAG SC 1.1.1.

Axe-core cannot determine if an image is decorative or informative. There is no reliable way to detect this, therefor axe-core cannot fail informative images that are marked up as decorative or vice versa. This is an unavoidable limitation of the technology. Axe-core can automatically find 57% of WCAG 2.0 issues, meaning that 43% of such issues need to be tested for manually or though tools like axe extensions Intelligent guided tests.