function IsNumeric(sText) {
  var ValidChars = "0123456789 ";
  var IsNumber=true;
  var Char;
  for (i = 0; i < sText.length && IsNumber == true; i++) {
    Char = sText.charAt(i);
    if (ValidChars.indexOf(Char) == -1) {
      IsNumber = false;
    }
  }
  return IsNumber;
}
function bookingform() {
  var emailfilter  = /^([a-zA-Z0-9_\.\-])+\@(([a-zA-Z0-9\-])+\.)+([a-zA-Z0-9]{2,4})+$/;
  var datefilter  = /[0-9][0-9]\-[0-9][0-9]/;
  if (!document.form1.name.value) {
    alert ("Please enter a name");
    document.form1.name.focus();
    return false;
  } else if (!document.form1.email.value) {
    alert ("Please enter an email address");
    document.form1.email.focus();
    return false;
  } else if (!emailfilter.test(document.form1.email.value)) {
    alert ("Please enter a valid email address");
    document.form1.email.focus();
    return false;
  }else if (!document.form1.tel.value) {
    alert ("Please enter a telephone number");
    document.form1.tel.focus();
    return false;
  } else if (!IsNumeric(document.form1.tel.value)) {
    alert ("Please enter a valid telephone number\nNumbers and spaces only");
    document.form1.tel.focus();
    return false;
  }else if (!document.form1.arriving.value) {
    alert ("Please use the \"Select Date\" function to select the dates\nDD-MM");
    document.form1.arriving.focus();
    return false;
  } else if (!datefilter.test(document.form1.arriving.value)) {
    alert ("Please use the \"Select Date\" function to select the dates\nDD-MM");
    document.form1.arriving.focus();
    return false;
  } else if (!document.form1.leaving.value) {
    alert ("Please use the \"Select Date\" function to select the dates\nDD-MM");
    document.form1.leaving.focus();
    return false;
  } else if (!datefilter.test(document.form1.leaving.value)) {
    alert ("Please use the \"Select Date\" function to select the dates\nDD-MM");
    document.form1.leaving.focus();
    return false;
  }
  else if (!document.form1.ayear.value) {
    alert ("Please indicate the year of arrival");
    document.form1.ayear.focus();
    return false;
  }
  else if (!document.form1.lyear.value) {
    alert ("Please indicate the year you intend to leave");
    document.form1.lyear.focus();
    return false;
  }else {
    return true;
  }
  return false;
}