フロントエンドサービスからのバックエンド要件の認証

document.getElementById("fn-btn").addEventListener("click", function(e) {
    e.preventDefault();
    var city = "test";
    var auth = catalyst.auth;
    auth.generateAuthToken().then((response) => {
            const token = response.access_token;
            fetch("URL_endpoint", {
                    <
                    !--URL end point of your backend service.-- >
                    method: "POST",
                    headers: {
                        Authorization: `${token}`,
                        "Content-Type": "application/json",
                    },
                    body: JSON.stringify({
                        city_name: city,
                    }),
                })
                .then((response) => response.json())
                .then((data) => {
                    alert(data.message);
                })
                .catch((err) => {
                    console.error("Error during fetch:", err);
                    alert("An error occurred. Please try again.");
                });
        })
        .catch((err) => {
            console.error("Error generating token:", err);
            alert("Failed to generate authentication token.");
        });
});