function validateEmail (email) {
    if (email.length == 0)
            return true;
    reg = /^[A-Z0-9_%\.\+\-]+@[A-Z0-9_\.\-]+\.[A-Z]{2,5}/i;
    return reg.test(email);
}

function isBlank(s) {
	return (s.replace(/ /g,"").length == 0);
}

function validateContactForm (f) {
    email = f.email.value.replace(/ /g,"");
    f.email.value = email;

    emailok = !isBlank(email);
    emailvalid = validateEmail(email);
    nameok = !isBlank(f.name.value);
    telephoneok = !isBlank(f.telephone.value);
    messageok = !isBlank(f.message.value);
    
    errors = new Array();
    if (!nameok) errors.push ("upišite svoje ime.");
    if (!emailok && !telephoneok) errors.push ("upišite e-mail adresu ili broj telefona.");
    if (!emailvalid && !telephoneok) errors.push ("upisana e-mail adresa nije ispravna.");
    if (!messageok) errors.push ("upišite poruku.");
    
    if (errors.length) {
    	msg = "Molimo Vas da ispravite sljedeće greške:";
    	for (var i=0; i<errors.length; i++) {
    		msg += "\n - " + errors[i];
    	}
    	alert (msg);
    	return false;
    } else {
    	return true;
    }
}