title: capture multiple "onkeydown" and wait until "onkeyup" to execute
body: <p>In my web app, I use the <strong>onkeydown</strong> event to capture key strokes.</p>
  
  <p>For example, I capture the 'j' key to animate a scroll down the page (and do some other stuff meanwhile).</p>
  
  <p>My problem is the user might keep the 'j' key down to scroll further down the page (this is equivalent to fast multiple key strokes).  </p>
  
  <p>In my app, this result in a series of animations that doesn't look that good.</p>
  
  <p>How can I know when the key has been released, and know the amount of key stokes I should have captured? This way I could run one long animation instead of multiple short ones.</p>