form_dang_ky.html

<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>Title</title>
</head>
<script src="Account_form.js"></script>
<body>
<div align="center">
    <h1>Form Đăng Ký</h1>
    Nhập username: <input id="username" placeholder="username"> <br>
    Nhập Password: <input id="password" placeholder="password" type="password"><br>
    <br>
    <button onclick="register()">Đăng ký</button>
</div>

</body>
</html>
<script>

    let accounts = JSON.parse(localStorage.getItem("accounts"));
    if (accounts === null) {
        accounts = [];
    }
    function register() {
        let username = document.getElementById("username").value;
        let password = document.getElementById("password").value;
        let account = new Account(username, password);
        accounts.push(account);
        localStorage.setItem("accounts", JSON.stringify(accounts));
        location.href = "form_dang_nhap.html";
    }
</script>