DialogFlow ES - Get the current time without user_input

What can I do, this code keeps showing Good Morning, but I was working on it in night. I also try what ChatGPT said used Intl.DateTimeFormat, but it's said undefined.

I want to get what is the problem of my code and the solution that I can used....

function welcome(agent) {
    const currentTime = new Date();
    const hour = currentTime.getHours(); 

    let greeting = "hello";
    if (hour >= 5 && hour < 12) {
        greeting = "Good morning.";
    } else if (hour >= 12 && hour < 18) {
        greeting = "Good afternoon.";
    } else if (hour >= 18 && hour < 22) {
    greeting = "Good evening.";
    } else {
        greeting = "Good night.";
    }
 
    agent.add(`🎵 ${greeting} my friend? I'm Si Kompang`);
    agent.add("May I know what is your name?");
    }

function welcome(agent) {

var date = new Date();
var hour = date.getHours() + 8; 

let greeting = "hello";
if (hour >= 5 && hour < 12) {
    greeting = "Good morning";
} else if (hour >= 12 && hour < 18) {
    greeting = "Good afternoon";
} else if (hour >= 18 && hour < 22) {
greeting = "Good evening";
} else {
    greeting = "Good night";
}

agent.add(`${greeting}, welcome to the world of musical instruments! I’m Pak Bung, the village head of kompang ethnicity. `);
agent.add("But before we start, may I know your name?😊");
}

This is the solution