// Declaring required variables
var digits = "0123456789";
// non-digit characters which are allowed in phone numbers
var phoneNumberDelimiters = "()- ";
// characters which are allowed in international phone numbers
// (a leading + is OK)
var validWorldPhoneChars = phoneNumberDelimiters + "+";
// Minimum no of digits in an international phone no.
var minDigitsInIPhoneNumber = 10;

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 ValidatePhone(phone){
	var Phone=phone
	
	if ((Phone.value==null)||(Phone.value=="")){
		alert("Please Enter your Phone Number")
		Phone.focus()
		return false
	}
	if (checkInternationalPhone(Phone.value)==false){
		alert("Please Enter a Valid Phone Number")
		Phone.value=""
		Phone.focus()
		return false
	}
	return true
 }

function isValidEmail(str) {
   return (str.indexOf(".") > 2) && (str.indexOf("@") > 0);
 
}

function checkF(form)
 {
    if (form.name.value=="") {alert("Enter name");  return false; }
	
    if (!(isValidEmail(form.e_mail.value))) {alert("Not a valid e-mail OR empty"); return false; }
	else
	{
		if (form.e_mail.value!=form.e_mail2.value) { alert("E-mails do not match"); return false; }
	}
    if(!ValidatePhone(form.phone)) {return false;}
    if (form.did_hear.value=="") {alert("Choose where did you heard about us!");  return false; }
    return true;
 }