twitch js bot subscription response

I am writing a bot for the twitch platform, and I want to make it respond to users who have subscribed to the channel.

I found USERNOTICE for this in the documentation https://dev.twitch.tv/docs/irc/commands#usernotice

But I didn't quite understand how to use it.

Something like this?

client.on("message", () => {
    client.say(config.get('channel'), '/usernotice message');
});

Just call the /usernotice command and it should respond to this subscription message?

It's just difficult to test all this and I would like to have a more or less specific solution.

UPDATE

Also in old documentation I found this code

chatClient.onSub((channel, user) => {
    chatClient.say(channel, `Thanks to @${user} for subscribing to the channel!`);
});

chatClient.onResub((channel, user, subInfo) => {
    chatClient.say(channel, `Thanks to @${user} for subscribing to the channel for a total of ${subInfo.months} months!`);
});

chatClient.onSubGift((channel, user, subInfo) => {
    chatClient.say(channel, `Thanks to ${subInfo.gifter} for gifting a subscription to ${user}!`);
});

But it throws an error - TypeError: client.onSub is not a function

Is there any way to use it now?

chatClient.on('sub', (channel, user) => {
    chatClient.say(channel, `Thanks to @${user} for subscribing to the channel!`);
});

Solution

On the assumption you are using tmi.js you should be looking at the tmi.js documentation rather than twitch's documentation. This documentation can be located here

in the documentation they have an example for a subscription event which can be found here: https://github.com/tmijs/docs/blob/gh-pages/_posts/v1.4.2/2019-03-03-Events.md#subscription

client.on("subscription", (channel, username, method, message, userstate) => {
    // Do your stuff.
});