regemail = /^([a-zA-Z0-9_\.\-])+\@(([a-zA-Z0-9\-])+\.)+([a-zA-Z0-9]{2,4})+$/;

function checkCheckBox(field_id, message_id, show){
  field   = document.getElementById(field_id);
  message = document.getElementById(message_id);
  if (field.offsetTop > 0 && field.checked != true){
    if (show){
      message.style.display="block";
    }
    form_check = false;
    return false;
  }
  return true;
}

function checkRegExpression(field_id, message_id, typelist, show){
  field   = document.getElementById(field_id);
  message = document.getElementById(message_id);
  if(field.offsetTop > 0 && !typelist.test(field.value)){
    if (show){
      message.style.display="block";
    }
    form_check = false;
    return false;
  }
  return true;
}

function checkSingleOption(field_id, message_id, value_name, value_cond, show){
  field   = document.getElementById(field_id);
  message = document.getElementById(message_id);
  result = field.options[field.options.selectedIndex].value;
  failed = false;
  if (value_cond == true){
  	if(result != value_name){
  		failed = true;
  	}
  }
  else{
  	if(result == value_name){
      failed = true;
    }
  }
  if(field.offsetTop > 0 && failed){
    if (show){
      message.style.display="block";
    }
    form_check = false;
    return false;
  }
  return true;
}