var name = new Array();
var price = new Array()

name[0] = 'THINK QUIT'; price[0] = '297';
name[1] = 'THINK SLIM'; price[1] = '347';
name[2] = 'THINK SLEEP'; price[2] = '197';
name[3] = 'THINK CALM'; price[3] = '60';
name[4] = '4 PROGRAM PACKAGE'; price[4] = '841';

var postage = 24.95;

function isInt(str) {
	var i = parseInt (str);

	if (isNaN (i))
		return false;

	i = i . toString ();
	if (i != str)
		return false;

	return true;
}

function add(itemno) {
	if (!document.forms[0].elements['qty' + itemno].value) {
		document.forms[0].elements['qty' + itemno].value = 1;
	}

	if (!isInt(document.forms[0].elements['qty' + itemno].value)) {
		document.forms[0].elements['qty' + itemno].value = '';
		delItem(itemno); return;
	}
	
	if (document.forms[0].elements['qty' + itemno].value <= 0) {
		delItem(itemno); return;
	}

	document.forms[0].elements['subtotal' + itemno].value = cent(Number(document.forms[0].elements['qty' + itemno].value) * price[itemno]);
	
	recalc();
}

function delItem(itemno) {
	document.forms[0].elements['qty' + itemno].value = '';
	document.forms[0].elements['subtotal' + itemno].value = '';
	recalc();

	if (total == 0) { 
		document.forms[0].total.value = '';
	}
}

function cent(amount) {
     amount -= 0;
     amount = (Math.round(amount*100))/100;
     return (amount == Math.floor(amount)) ? amount + '.00' : (  (amount*10 == Math.floor(amount*10)) ? amount + '0' : amount);
}

function recalc() {
	total = 0;
	for (i = 0; i < name.length; i++) {
		if (document.forms[0].elements['qty' + i].value > 0) {
			var sub = Number(document.forms[0].elements['qty' + i].value) * price[i];
			document.forms[0].elements['subtotal' + i].value = cent(sub);
			total = sub + total;
		}else {
			document.forms[0].elements['qty' + i].value = '';
		}
	}
	document.forms[0].total.value = '$' + cent(total + postage);
	if (total > 0)
		document.forms[0].postage.value = cent(postage);
	else
		document.forms[0].postage.value = '';
}