fixed style use javascirpt

fixed style use javascirpt

/* It is not possible to get certain styles set in css such as display using 
the normal javascript.  So we have to use this function taken from:
http://www.quirksmode.org/dom/getstyles.html */
function getStyle(el,styleProp)
{
   var x = document.getElementById(el);
   if (x.currentStyle) // IE
      var y = x.currentStyle[styleProp];
   else if (window.getComputedStyle)  // FF

      var y = document.defaultView.getComputedStyle(x,null).getPropertyValue(styleProp);
   return y;
}

function your_popup_function()
{
 div_id = 'helpwindow';
 
 if (getStyle(div_id, 'left') == '1px') // only scroll if mobile. This is set in mobile.css
   {
      move_alert(div_id);
      window.onscroll = function()
      {
         move_alert(div_id);
      }
   }
}

function move_alert(div_id)
{
   // get current top 
   if (document.documentElement.scrollTop) // Needed if you use doctype loose.htm

      current_top = document.documentElement.scrollTop;
   else
      current_top = document.body.scrollTop;

   // get current bottom
   if (document.documentElement.clientHeight) // Needed if you use doctype loose.htm
      current_bottom =  current_top + document.documentElement.clientHeight;
   else

      current_bottom = current_top + document.body.clientHeight;

   alert_div = document.getElementById(div_id);
   alert_div.style.position = 'absolute';
   // alert_div.style.top = current_bottom - alert_div.offsetHeight; // Not working on iphone
   alert_div.style.top = current_top;
} // end function move_alert(div_id)