ecshop清空购物车时怎么加上提醒

<input type="button" value="{$lang.clear_cart}" class="bnt_blue_1" onclick="location.href='flow.php?step=clear'" />

<script type = "text/javascript" language = "javascript">
function clear1()
{
if(confirm("您确定要清空购物车吗？"))
{
window.location.href="flow.php?step=clear";
}
}
</script>

<input type="button" value="{$lang.clear_cart}" class="bnt_blue_1" onclick="location.href='flow.php?step=clear'" />

<input type="button" value="{$lang.clear_cart}" class="bnt_blue_1" onClick="return clear1();" />