title: Javascript - detect or override all onkeyup and onkeydown handlers
body: <p>In javascript, is there a way to detect or override (to 'null') all onkeyup and onkeydown handlers applied to DOM elements, rather than iterate the entire dom?</p>
  
  <p>(I this scenario, I'm looking to override onkey handlers that extensions may have inserted onto the DOM, e.g. by browser extensions, rather than detect handlers added by the site directly).</p>