function eCheckEMail(sn){
    s= sn.value;
    if (s.indexOf("@") == -1) return false;
    if (s.indexOf(".") == -1) return false;
    at=false;
    dot=false;
    for (var i = 0; i < s.length; i++) {
        ch = s.substring(i, i + 1)
        if ((ch >= "A" && ch <= "Z") || (ch >= "a" && ch <= "z")
                || (ch == "@") || (ch == ".") || (ch == "_")
                || (ch == "-") || (ch >= "0" && ch <= "9")) {
                if (ch == "@"){
                  if (at) return false;
                  else at=true;
                }
                if ((ch==".") && at)
                   dot=true;
        }
        else return false;
    }
   return dot;
}

function checkForm(myForm){

      for(i=0; i<myForm.elements.length; i++){
          if(myForm.elements[i].type=='text'&&myForm.elements[i].name=='_user[email]')
             email = myForm.elements[i];
          if(myForm.elements[i].type=='checkbox'&&myForm.elements[i].name=='_user[news]')
             news = myForm.elements[i].checked;
          if(myForm.elements[i].type=='checkbox'&&myForm.elements[i].name=='_user[sk_news]')
             sk_news = myForm.elements[i].checked;
          if(myForm.elements[i].type=='hidden'&&myForm.elements[i].name=='act')
             return true;

      }

      if(email.value.length>0&&!eCheckEMail(email)){
          alert ('Nezadal jste správnou e-mailovou adresu.\n\nOpravte, prosím, adresu.');
          return false;
      }

      if((email.value.length<1 || !eCheckEMail(email)) && (news || sk_news)){
          alert ('Chystáte si zadat zasílání novinek, ale nezadal jste správnou e-mailovou adresu.\n\nOpravte, prosím, adresu');
          return false;
      }

      return true;

}


function changeBackground(where, color, cursor){

         where.style.background = color;
         where.style.cursor = cursor;

}