3_custom.js

// [...]
function checkAuthState() {
    if (!user.value) {
        document.getElementById("login-block").style.display = "grid"
        document.getElementsByClassName("message-container")[0].style.display = "none";
    } else {
        document.getElementsByClassName("message-container")[0].style.display = "grid";
        document.getElementById("login-block").style.display = "none"
        username = user.value

        initializeClient() // initiaize client
    }
}

const user = document.getElementById("user-login-input")
user.addEventListener("keyup", function(event) {
    if (event.key === "Enter") {
        checkAuthState()
    }
});
checkAuthState()