<script type="text/javascript">
var num=[3.3,-0.1,-9.9,8.9];
for(var i=0 i<=num.length i++)
{
document.write(Math.ceil(num[i]));
}
</script>
for循环条件里要分号隔开
for(var i=0; i<=num.length; i++)
循环条件后面少一个分号;