<html>
<head>
</head>
<body>
<input id="kolvo">
<button class="border" onclick="card.addToCard(this, '002', 'Зонт1', '1500', kolvo.value)">Купить</button>
<script>
card={
addToCard: function(env, foo, bar, baz, plat){alert(plat)}
}
</script>
</body>
</html>