获取checked的值

<p>你喜欢怎么喝咖啡？</p>
<form>
<input type="checkbox" name="coffee" value="奶油">加奶油<br />
<input type="checkbox" name="coffee" value="糖块">加糖块<br />
<br />
<input type="button"  value="发送订单">
<br /><br />
<input type="text" id="order" size="50">
<script>
function createOrder()
{
coffee=document.forms[0].coffee
txt=""
for (i=0;i<coffee.length;++ i)
{
if (coffee[i].checked)
{
txt=txt + coffee[i].value + " "
}
}
document.getElementById("order").value="您订购的咖啡带有： " + txt
}
</script>