// this function returns true if sthe string is blank

function isblank(s)
{
	for(var i = 0; i < s.length; i++) {
		var c = s.charAt(i);
		if ((c != ' ') && (c != '\n') && (c != '\t')) return false
	}
	return true
}

// this function performs form verification

function verify(f)
{
	var description = new Array();
		description[0] = "Email address";

	var msg;
	var empty_fields = "";
	var errors = "";
	
for(var i = 0; i < f.length; i++) {
	var e = f.elements[i];
// check if the field is empty
	if ((e.value == null) || (e.value == "") || isblank(e.value)) {
		empty_fields += "\n          " + description[i];
		continue;
	}

	
}


// check email address

if (f.address.value!="")
{if (f.address.value.indexOf("@")==-1 || f.address.value.indexOf(".")==-1 || f.address.value.indexOf(" ")!=-1 || f.address.value.length<6) {
		errors += "It doesn't seem a valid email address";
		errors += ".\n";
	}
	}


	
if (!empty_fields && !errors) return true;

msg = "Please type in your email address"


if (empty_fields) {

	alert(msg);
	return false;
	}



if (errors) {

	alert(errors);

	return false;		
	}

	
	
}