Learning JavaScript, 3rd Edition

Chapter 19. Node

Up until 2009, JavaScript was almost exclusively a browser scripting language.¹ In 2009, frustrated by the state of server-side options, a Joyent developer named Ryan Dahl created Node. Node’s adoption was meteoric, and it even achieved success in the notoriously slow-to-adopt enterprise markets.

For those who liked JavaScript as a language, Node made it possible to use the language for tasks traditionally relegated to other languages. For web developers, the appeal is stronger than just the choice of language. Being able to write JavaScript on the server means a consistent language choice—no mental context-switching, a reduced reliance on specialists, and (perhaps most importantly) the ability to run the same code on the server and the client.

While Node was introduced to enable web application development, its jump to the server inadvertently enabled other nontraditional uses, such as desktop application development and system scripting. In a sense, Node allowed JavaScript to grow up and join the party.

Node Fundamentals

If you can write JavaScript, you can write Node applications. That’s not to say that you can simply take any browser-based JavaScript program and run it on Node: browser-based JavaScript uses APIs that are specific to the browser. In particular, in Node, there is no DOM (which makes sense: there’s no HTML). Likewise, there are APIs that are specific to Node that don’t exist in the browser. Some, like operating system and filesystem ...