<form name="zhuce" onSubmit="return checkform();" action="">
帐号<input type="text" name="T1" size="20"><br>
<input type="submit" value="提交" name="B1">
</form>
<script language="javascript">
function checkform()
{
if (this.T1.value==''){alert('用户名不能为空!');return false;}
}
</script>
參考答案:this.T1.value
改成
this.zhuce.T1.value