title: Where is the basis for negative tabindex being focusable?
body: <p>I found focus() information on <a href="https://developer.mozilla.org/en-US/docs/Web/HTML/Global_attributes/tabindex" rel="nofollow noreferrer">MDN</a> ...</p>
  
  <blockquote>
    <p>but a script can do so by calling the <code>focus()</code> method.</p>
  </blockquote>
  
  <p>Is this clearly defined in the specification?</p>
  
  <p>There are several conditions for focusable, but the <a href="https://html.spec.whatwg.org/multipage/interaction.html#focusable-area" rel="nofollow noreferrer">following conditions</a> are most likely to be met.</p>
  
  <blockquote>
    <p>Any other element or part of an element determined by the user agent to be a focusable area, especially to aid with accessibility or to better match platform conventions. </p>
  </blockquote>
  
  <p>However, since this depends on the judgment of each browser vendor, I thought that it could not be the basis that the negative tabindex is focusable.</p>
  
  <p>Since there are currently no browsers where negative tabindex is not focusable, can we say that negative tabindex is focusable?</p>