دانلود کتاب یادگیری Node.js – ویرایش دوم

Welcome to Learning Node.js. Node.js is an exciting platform for writing applications of all sorts, ranging from powerful web applications to simple scripts you can run on your local computer. The project has grown from a reasonably small software package managed by one company into a production-quality system governed by a Technical Steering Committee (TSC) and has a sizeable following in the developer community. In this book, I teach you more about it and why it is special, then get you up and writing Node.js programs in short order. You’ll soon find that people are rather flexible with the name of Node.js and will refer to it frequently as just Node or even node. I certainly do a lot of that in this book as well. Node.js has arisen for a couple of primary reasons, which I explain next. In the past, writing web applications was a pretty standard process. You have one or more servers on your machine that listen on a port (for example, 80 for HTTP), and when a request is received, it forks a new process or a thread to begin processing and responding to the query. This work frequently involves communicating with external services, such as a database, memory cache, external computing server, or even just the file system. When all this work is finally finished, the thread or process is returned to the pool of available servers, and more requests can be handled.