title: How do i get relative dimensions of scrollbale window viewport
body: <p>I am having a Tooltip (larger image view) that is being positioned via e.pageX e.pageY and i am trying to make sure it is not hidden below the current scrolled view port.</p>
  
  <p>I have seen many sites have this
  my code is something like this but i am missing something.</p>
  
  <pre><code>var positionImg = function(e) {
      var viewportWidth = $(window).width(); 
      var viewportHeight = window.innerHeight ? window.innerHeight : $(window).height();  
      var mouseAtY = e.pageY;
      var mouseAtX = e.pageX;
      var maxBottomVPos = viewportHeight-"i dont know";
      var maxTopVPos = 30;
  
      if (mouseAtY &gt;= maxBottomVPos)
      {
          tPosX = mouseAtX+ 10;
          tPosY = mouseAtY -520;
      }
      else if (mouseAtY &lt;= maxTopVPos)
      {
          tPosX = mouseAtX;
          tPosY = mouseAtY +40;
      }
      else
      {
          tPosX = mouseAtX;
          tPosY = mouseAtY +20;  
      }
      $zoomContainer.css({top: tPosY, left: tPosX});
  };
  </code></pre>