// JavaScript Document
function layerswap(layername){

  if(document.getElementById(layername))
  {
   alert(layername);
    if (document.getElementById(layername).style.visibility=='visible')
    {
        alert('useless');
      document.getElementById(layername).style.visibility='hidden';
      document.getElementById(layername).style.display='none';
    }else
    {
        alert('hi');
        alert(document.getElementById(layername).style.visibility);  
      document.getElementById(layername).style.visibility='visible';
      document.getElementById(layername).style.display='block';
       alert(document.getElementById(layername).style.visibility);  
    }
  }
}