<%@ page language="java" contentType="text/html; charset=gb2312"
pageEncoding="gb2312"%>
<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN">
<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=gb2312">
<title>测试JavaScript </title>
</head>
<script language="JavaScript">
function check()
{
alter("DDDDDDDDD");
if(document.form1.user.value="")
{
alter("用户名不能为空");
return;
}
}
</script>
<body>
<form action="test.jsp" name="form1" method="post" onClick="check()">
<table>
<tr>
<td>用户名 </td>
<td>
<input type="text" name="user">
</td>
</tr>
<tr>
<td>密 码 </td>
<td>
<input type="password" name="pw">
</td>
</tr>
<tr>
<td colspan="2">
<p align="center">
<input type="submit" name="ok" value="提交">
<input type="reset" name="cancel" value="重置">
</p>
</td>
</tr>
</table>
</form>
</body>
</html>
请问这段代码为何不执行输入框的有效性检查？另我在不同的机器上上述代码还会报对象不可用或错误的警告框，应该是JavaScript函数的if判断语句那边，请指教，谢谢！
