Data event not firing Node.js

Question

I'm writing an application that downloads YouTube videos with the extension node-ytdl. I'd like to send the client a progress indicator on the download, so I'm trying to get chunk information to compute it. My code looks kind of like this.

        var writing = fs.createWriteStream('video.mp4');
        var stream = ytdl('https://www.youtube.com/watch?v=jofNR_WkoCE', { filter: function(format) { return format.container === 'mp4'; }, quality: "lowest" });
        stream.pipe(writing);

        var completed_len = 0;
        var total_len = 0;

        writing.on('data', function(chunk) {
            console.log('received data!');
            completed_len += chunk.length;
        });

        writing.on('close', function ()
        {
            console.log('close');
            res.send('completed!');
        });

Weirdly enough, even though 'close' fires whenever the download is done, I'm not getting any logs from the 'data' event. The video is written correctly. I'm kind of new to Node.js streams. Have I done something wrong?

Answer 1

You've just bound to the wrong stream. 'data' events will occur on readable streams, like the stream created by ytdl.

stream.on('data', function (chunk) {
    // ...
});

And 'close' events will occur on both streams if you're using Node 0.8 or older. While 0.10 changed the event for writable streams to 'finish'.