function changeLang() {
 var currURL = ""+document.location;
 var newURL = currURL;
 var charloc = newURL.indexOf('#');
 if (currURL.match(/\/eng\//))
  newURL = currURL.replace(/\/eng\//, "/chi/");
 else if (currURL.match(/\/chi\//))
  newURL = currURL.replace(/\/chi\//, "/eng/");
 if (charloc > 0)
    document.location = newURL.substring(0, charloc);
 else
    document.location = newURL;
}