var cookiename = "usinfosession";

var allcookies = document.cookie;
var pos = allcookies.indexOf(cookiename+'=');
if (pos == -1) {
  var chars = "0123456789ABCDEFGHIJKLMNOPQRSTUVWXTZabcdefghiklmnopqrstuvwxyz";
  var randomstring = '';
  for (var i=0; i<20; i++) {
    var rnum = Math.floor(Math.random() * chars.length);
    randomstring += chars.substring(rnum,rnum+1);
  }
  document.cookie = cookiename + "=" + escape(randomstring) + ";path=/";
}