这是一个验证表单的实例,但是没有输入用户名和密码,点提交时,没有弹出警告框,怎么回事啊<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN">
<html>
<head>
<title>CheckForm.html</title>
<script language="javascript">
function checkForm()
{
//定义一个变量
var theForm=document.test;
if(theForm.username.value="")
{
alert("请输入用户名!");
theForm.username.focus();
}
else if(theForm.pwd.value="")
{
alert("请输入密码!");
theForm.pwd.focus();
}
else
{
theForm.submit();
}
}
</script>
</head>
<body>
<form name="test" method="post" action="login.jsp">
用户名:<input type="text" name="username"/>
<br/>
密码:<input typt="password" name="pwd"/>
<br/>
<input type="button" value="提交"
onclick="javascript:checkForm()">
</form>
</body>
</html>
<html>
<head>
<title>CheckForm.html</title>
<script language="javascript">
function checkForm()
{
//定义一个变量
var theForm=document.test;
if(theForm.username.value="")
{
alert("请输入用户名!");
theForm.username.focus();
}
else if(theForm.pwd.value="")
{
alert("请输入密码!");
theForm.pwd.focus();
}
else
{
theForm.submit();
}
}
</script>
</head>
<body>
<form name="test" method="post" action="login.jsp">
用户名:<input type="text" name="username"/>
<br/>
密码:<input typt="password" name="pwd"/>
<br/>
<input type="button" value="提交"
onclick="javascript:checkForm()">
</form>
</body>
</html>
if(theForm.username.value="")改为 if(theForm.username.value=="")
else if(theForm.pwd.value="") 改为else if(theForm.pwd.value=="")