function validate_required(field,alerttxt)
{
with (field)
  {
  if (value==null||value=="")
    {
    alert(alerttxt);return false;
    }
  else
    {
    return true;
    }
  }
}

function validate_form(thisform)
{
with (thisform)
  {
  if (validate_required(bookerName,"Name is required.")==false)
  {bookerName.focus();return false;}
  if (validate_required(bookerEmail,"Email is required.")==false)
  {bookerEmail.focus();return false;}
  }
}