Question

Im reading this article: http://elegantcode.com/2011/04/06/taking-baby-steps-with-node-js-pumping-data-between-streams/ and having some slight troubles understanding streams.

Quote:

"Suppose we want to develop a simple web application
that reads a particular file from disk and send it to the browser.
The following code shows a very simple and naïve implementation
in order to make this happen."

So the code sample is as follows:

var readStream = fileSystem.createReadStream(filePath);
readStream.on('data', function(data) {
    response.write(data);
});

readStream.on('end', function() {
    response.end();        
});

Why would we use that above way when we could simply do:

fs.readFile(filePath, function(err, data){
  response.write(data);
  response.end();
});

When or why would I use streams?

Answer 1

You’d use stream when working with large files. With a callback, all of the file’s contents must be loaded into memory at once, while with a stream, only a chunk of the file is in memory at any given time.

Also, the stream interface is arguably more elegant. Instead of explicitly attaching data, drain, and end callbacks, you can instead use pipe:

var readStream = fileSystem.createReadStream(filePath);
readStream.pipe(response);