function trim(s)
{
  // Remove leading spaces and carriage returns
  while ((s.substring(0,1) == ' ') || (s.substring(0,1) == '\n') || (s.substring(0,1) == '\r'))
  {
    s = s.substring(1,s.length);
  }

  // Remove trailing spaces and carriage returns
  while ((s.substring(s.length-1,s.length) == ' ') || (s.substring(s.length-1,s.length) == '\n') || (s.substring(s.length-1,s.length) == '\r'))
  {
    s = s.substring(0,s.length-1);
  }
  return s;
}


function checkValues(){

    form = document.form_tkbasv_ekle;
    errs = "";
    if (trim(form.f_ad.value) == '') { errs += "\n - Firma Adı "; }
    if (trim(form.f_mail.value) == '' || !isValidEmail(form.f_mail.value)  ) { errs += "\n - İletişim E-Posta Adresi "; }
    if (trim(form.f_tel.value) == '') { errs += "\n - Firma Telefonu "; }
    if (errs != '') {
        alert("Lütfen aşağıdaki alanları boş bırakmayınız.\n" + errs);
        return false;
    }
	form.submit();
}


function isValidEmail(email, required) {
    if (required==undefined) {   // if not specified, assume it's required
        required=true;
    }
    if (email==null) {
        if (required) {
            return false;
        }
        return true;
    }
    if (email.length==0) {
        if (required) {
            return false;
        }
        return true;
    }
    if (! allValidChars(email)) {  // check to make sure all characters are valid
        return false;
    }
    if (email.indexOf("@") < 1) { //  must contain @, and it must not be the first character
        return false;
    } else if (email.lastIndexOf(".") <= email.indexOf("@")) {  // last dot must be after the @
        return false;
    } else if (email.indexOf("@") == email.length) {  // @ must not be the last character
        return false;
    }

    return true;
}

function allValidChars(email) {
  var parsed = true;
  var validchars = "abcdefghijklmnopqrstuvwxyz0123456789@.-";
  for (var i=0; i < email.length; i++) {
    var letter = email.charAt(i).toLowerCase();
    if (validchars.indexOf(letter) != -1)
      continue;
    parsed = false;
    break;
  }
  return parsed;
}