In Node.js can socket.io listen to multiple event?

I am newbie to Node.js, actually I'm new to front end.

I am writing Node.js code to visualize data on the browser.

Below is the a piece of code:

    var socket = io();
    socket.on('data', function (data) {
        newDataCallback(data);
    });

    socket.on('tweet', function (tweet) {
        console.log('received tweet' + tweet);
        newTweetCallback(tweet);
    });

When I debug in Chrome, I found only the second socket.on was processing the data, but the first socket.on was skipped. I had a feeling that socket.on only only listen to one event at a time. Is it correct? How to listen and process on multiple event? Thank you for answering me this basic question.

Thank you!

via hpnhxxwn