<form name="myform" action="###" method="post" onsubmit="check()">
<label for="name"> 账号:</label><input type="text" size="20" value="" placeholder="请输入账号" name="name" id="name" /><br />
<label for="pw" > 密码:</label><input type="password" id="pw" name="pw" placeholder="请输入密码" value="" /><br />
<input type="submit" value="登录" /><input type="reset" value="重置" />
</form>
From 的onsubmit应该是 onsubmit="return check()"
事件里面要返回一个布尔值
代码不完整,看看调试下呢