Book Image

Mastering Node.js

By : Sandro Pasquali
Book Image

Mastering Node.js

By: Sandro Pasquali

Overview of this book

Node.js is a modern development stack focused on providing an easy way to build scalable network software. Backed by a growing number of large companies and a rapidly increasing developer base, Node is revolutionizing the way that software is being built today. Powered by Google's V8 engine and built out of C++ modules, this is a JavaScript environment for the enterprise.Mastering Node.js will take the reader deep into this exciting development environment. Beginning with a comprehensive breakdown of its innovative non-blocking evented design, Node's structure is explained in detail, laying out how its blazingly fast I/O performance simplifies the creation of fast servers, scalable architectures, and responsive web applications.Mastering Node.js takes you through a concise yet thorough tour of Node's innovative evented non-blocking design, showing you how to build professional applications with the help of detailed examples.Learn how to integrate your applications with Facebook and Twitter, Amazon and Google, creating social apps and programs reaching thousands of collaborators on the cloud. See how the Express and Path frameworks make the creation of professional web applications painless. Set up one, two, or an entire server cluster with just a few lines of code, ready to scale as soon as you're ready to launch. Move data seamlessly between databases and file systems, between clients, and across network protocols, using a beautifully designed, consistent, and predictable set of tools.Mastering Node.js contains all of the examples and explanations you'll need to build applications in a short amount of time and at a low cost, running on a scale and speed that would have been nearly impossible just a few years ago.
Table of Contents (20 chapters)
Mastering Node.js
About the Author
About the Reviewers

Writing to a file

As with reading files, Node provides a rich collection of tools for writing to files. We'll see how Node makes it as easy to target a file's contents byte-by-byte, as it is to pipe continuous streams of data into a single writable file.

Writing byte by byte

The fs.write method is the most low-level way Node offers for writing files. This method gives us precise control over where bytes will be written to in a file.

fs.write(fd, buffer, offset, length, position, callback)

To write the collection of bytes between positions 309 and 8675 ( length 8366) of buffer to the file referenced by file descriptor fd, insertion beginning at position 100:

var buffer = new Buffer(8675);"index.html", "w", function(err, fd) {
  fs.write(fd, buffer, 309, 8366, 100, function(err, writtenBytes, buffer) {
    console.log("Wrote " + writtenBytes + " bytes to file");
    // Wrote 8366 bytes to file


Note that for files opened in append (a) mode some operating systems may ignore...