HTML Checking for Large Sites

Rocket Validator automatically checks your pages on the W3C Validator.

The “sizes” attribute may be specified only if the “srcset” attribute is also present.

The sizes attribute is used to complement the srcset attribute on an <img> tag for responsive images, therefore it’s not valid if srcset is missing. Check the HTMLImageElement.srcset guide to learn about the correct usage of the srcset and sizes attributes.

Related W3C validator issues

When the “srcset” attribute has any image candidate string with a width descriptor, the “sizes” attribute must also be present.

When was the last time you validated your whole site?

Keep your sites healthy checking for A11Y/HTML issues on an automated schedule.

Rocket Validator Pro
50000 A11Y / HTML checks, $48/month