js两个if嵌套在一起是如何运行的？
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>
素胚勾勒不出你2回答
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慕田峪9158850
-
慕标5832272
var username = loginform.username.value != "";var password = loginform.password.value != "";if(!username ){ alert('用户名不能为空');}if(!password){ alert('密码不能为空');}return username && password;
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相关分类
JavaScript