title: Activate an element's :active CSS pseudo-class using Javascript?
body: <p>Is this possible?</p>
  
  <p>For example, if a user presses the "return" key and I trigger the "mousedown" event, how do I also render the element with :active styles?</p>
  
  <p>I know it is possible to do this using classes, but I'd greatly prefer to use the pre-existing :active styles.</p>