function  ValidateForm() {
	if(document.enquiry.room.value=="Select type"){
		alert("Please select -> Room type");
		document.enquiry.room.focus();
		return false;
	}
	if (document.enquiry.number.value=="") {
	    alert("Please Enter -> Total no of persons");
		document.enquiry.number.focus();
		return false;
    }
	if (document.enquiry.checkin.value=="") {
	    alert("Please Enter -> Check in Date");
		document.enquiry.checkin.focus();
		return false;
    }
    if (document.enquiry.checkout.value=="") {
	    alert("Please Enter -> Check out Date");
		document.enquiry.checkout.focus();
		return false;
    }
    if (document.enquiry.arivaltime.value=="") {
	    alert("Please Enter -> Estimated Arrival Time");
		document.enquiry.arivaltime.focus();
		return false;
    }	
    if (document.enquiry.fname.value=="") {
	    alert("Please Enter -> First Name");
		document.enquiry.fname.focus();
		return false;
    }
	if (document.enquiry.lname.value=="") {
	    alert("Please Enter -> Last Name");
		document.enquiry.lname.focus();
		return false;
    }
	if (document.enquiry.gender.value=="Select") {
	    alert("Please Enter -> Select Gender");
		document.enquiry.gender.focus();
		return false;
    }	
	if (document.enquiry.nationality.value=="") {
	    alert("Please Enter -> Nationality");
		document.enquiry.nationality.focus();
		return false;
    }
	if (document.enquiry.email.value=="") {
	    alert("Please Enter -> Email");
		document.enquiry.email.focus();
		return false;
    }
	if (document.enquiry.mobile.value=="") {
	    alert("Please Enter -> Contact Phone");
		document.enquiry.mobile.focus();
		return false;
    }
	if (document.enquiry.comments.value=="") {
	    alert("Please Enter -> Comments / Additional Requests");
		document.enquiry.comments.focus();
		return false;
    }
	
	if (document.enquiry.checkin.value > document.enquiry.checkout.value) {
		alert ("Check out date  must be greater than Check in date");
		document.enquiry.checkout.focus();
		return false;
	}

}

<!--  checking valid email address-->		
function validmail(obj) {								 
	var EmailOk  = true
	var Temp     = obj
	var AtSym    = Temp.value.indexOf('@')
	var Period   = Temp.value.lastIndexOf('.')
	var Space    = Temp.value.indexOf(' ')
	var Length   = Temp.value.length - 1   // Array is from 0 to length-1
	if(obj.value !="") {
		if ((AtSym < 1) ||                     // '@' cannot be in first position
			(Period <= AtSym+1) ||             // Must be atleast one valid char btwn '@' and '.'
		    (Period == Length ) ||             // Must be atleast one valid char after '.'
		    (Space  != -1))                    // No empty spaces permitted
		   {  
		      EmailOk = false
		      alert("Please enter a valid e-mail address!");
		      Temp.value="";
		      Temp.focus();
	      	return EmailOk;
		}
	}
}

	var digits = "0123456789";
	var phoneNumberDelimiters = "()- ";
	var validWorldPhoneChars = phoneNumberDelimiters + "+";
	var minDigitsInIPhoneNumber = 6;
function isInteger(s) {   
	var i;
    for (i = 0; i < s.length; i++) {   
        // Check that current character is number.
        var c = s.charAt(i);
        if (((c < "0") || (c > "9"))) return false;
    }
    // All characters are numbers.
    return true;
}

function stripCharsInBag(s, bag) {   
	var i;
    var returnString = "";
    // Search through string's characters one by one.
    // If character is not in bag, append to returnString.
    for (i = 0; i < s.length; i++) {   
        // Check that current character isn't whitespace.
        var c = s.charAt(i);
        if (bag.indexOf(c) == -1) returnString += c;
    }
    return returnString;
}
function checkInternationalPhone(strPhone) {
	s=stripCharsInBag(strPhone,validWorldPhoneChars);
	return (isInteger(s) && s.length >= minDigitsInIPhoneNumber);
}
function validphone() {
	var Phone=document.enquiry.phone
	if (checkInternationalPhone(Phone.value)==false) {
		alert("Please Enter a Valid Phone Number")
		phone.value=""
		phone.focus()
		return false
	}
	return true
 }
// JavaScript Document
function ValidateGuestBook() {
	if (document.guestbook.name.value=="") {
	    alert("Please Enter -> Name");
		document.guestbook.name.focus();
		return false;
    }
	if (document.guestbook.email.value=="") {
	    alert("Please Enter -> Email");
		document.guestbook.email.focus();
		return false;
    }
	if (document.guestbook.comment.value=="") {
	    alert("Please Enter -> Comment");
		document.guestbook.comment.focus();
		return false;
    }
}