HTML Checking for Large Sites

Rocket Validator automatically checks your pages on the W3C Validator.

Bad value “X” for attribute “for” on element “label”: An ID must not contain whitespace.

The <label> element represents a caption in a document, and it can be associated with a form input using the for attribute, which must be an ID. Document IDs cannot contain whitespace.


  <label for="user_name">Name</label>
  <input type="text" id="user_name" />

Learn more:

Related W3C validator issues

50,000 Accessibility and HTML checks per month. Fully automated.

Let our automated scanner check your large sites using Axe Core and W3C Validator.