Code help for my simple Node.js chatbot?

Chat and IRC
8

channel starts with “#” – you must remove it from the variable, use a second variable, or add “#” to your channel names.

client.on('subscription', function(_channel, username, method, message, userstate) {
    let channel = _channel.slice(1);
    let output = '';
    switch(channel) {
        case 'channel1':
            output = 'Thanks for the sub to ' + channel;
        case 'channel2':
            output = 'Wowza! Thank you for the sub, ' + (userstate['display-name'] || username);
        case 'channel3':
            output = username + ' just subbed to ' + channel + '!';
    }
    if(output) client.say(channel, output);
});