Comma처리

(function comma(str){
  var s = str.split(',');
  if(/(\d){4}/.test(s)){
    s[0] = s[0].replace(/(\d){3}(,|\.|$)/,',\$&');
    s[0] = comma(s[0]);
   }
   return s.join('.');
})("1234567890.12");