>我正在用HTML和javascript创建一个基本的登录程序，我想我输入了正确的用户名和密码，但程序不断返回失败警报。我将不胜感激。
*HTML/JS 代码**
var username = "jeff"
var password = "whatever"
function login() {
var possible_username = document.getElementById("username");
var possible_password = document.getElementById("password");
if (username == possible_username && password == possible_password) {
alert("you have successfully logged in!");
} else {
alert("you failed to log in !");
}
}<!DOCTYPE html>
<html>
<head>
<title>website</title>
<link rel="stylesheet" href="styles.css">
</head>
<body>
<input id="username">
<input id="password">
<button onclick="login()">login</button>
<script src="script.js"></script>
</body>
</html>document.getElementById("username")返回 HTML 对象，要获取username，您需要从对象中获取值，因此请改用document.getElementById("username").value。
密码也是如此。见下面的片段
var username = "jeff";
var password = "whatever";
function login() {
var possible_username = document.getElementById("username").value;
var possible_password = document.getElementById("password").value;
if (username == possible_username && password == possible_password) {
alert("you have successfully logged in!");
} else {
alert("you failed to log in !");
}
}<!DOCTYPE html>
<html>
<head>
<title>website</title>
<link rel="stylesheet" href="styles.css">
</head>
<body>
<input id="username">
<input id="password">
<button onclick="login()">login</button>
<script src="script.js"></script>
</body>
</html>您需要像这样使用输入的值：
附言您也可以使密码输入类型密码
var username = "jeff"
var password = "whatever"
function login() {
var possible_username = document.getElementById("username").value;
var possible_password = document.getElementById("password").value;
if (username == possible_username && password == possible_password) {
alert("you have successfully logged in!");
} else {
alert(`you failed to log in with username ${possible_username} and password ${possible_password} !`);
}
}<!DOCTYPE html>
<html>
<head>
<title>website</title>
<link rel="stylesheet" href="styles.css">
</head>
<body>
<input id="username">
<input id="password" type="password">
<button onclick="login()">login</button>
<script src="script.js"></script>
</body>
</html>