Is a url query parameter valid if it has no value?

Question

Is a url like http://example.com/foo?bar valid?

I\'m looking for a link to something official that says one way or the other. A simple yes/no answer or

Answer 1

isindex deprecated magic name from HTML5

This deprecated feature allows a form submission to generate such an URL, providing further evidence that it is valid for HTML. E.g.:

  
  Submit

generates an URL of type:

?bar

Standard: https://www.w3.org/TR/html5/forms.html#naming-form-controls:-the-name-attribute

isindex is however deprecated as mentioned at: https://stackoverflow.com/a/41689431/895245