如这个登录验证的例子，两个if嵌套在一起是怎么运行的？
<!DOCTYPE html>
<html>
<head>
<title>login</title>
<meta charset="utf-8">
</head>
<body>
<form id="loginform" name='loginform' onsubmit="return checkLogin()">
<div>
<label for="username">账号：</label>
<input type="text" id="username" name="username">
</div>
<div>
<label for="password">密码：</label>
<input type="password" id="password" name="password">
</div>
<input type="submit" value="登录">
</form>
<script type="text/javascript">
//验证登录
function checkLogin() {
if (loginform.username.value != "") {
if (loginform.password.value != "") {
return ture
} else {
alert('密码不能为空');
return false
}
} else {
alert('用户名不能为空');
return false
}
}
</script>
</body>
</html>
慕田峪9158850
慕标5832272
相关分类