What is Node.js?

Node.js lets you run JavaScript outside of the browser, on your computer or a server.

Node.js was created by Ryan Dahl and released in 2009. He presented it at JSConf that year in a talk that became famous in the developer community. JavaScript was originally designed to run only in web browsers, where it could make pages interactive. Ryan took the V8 engine that powers Chrome and built a way to run JavaScript outside the browser entirely.

This was a big deal. Before Node.js, if you wrote JavaScript in the browser, you still needed to learn a separate language like PHP, Ruby, or Java to build the server side of your app. Node.js made it possible to use JavaScript for everything. The idea of a true full-stack JavaScript developer suddenly made sense.

Node.js was also a big deal because it was built for async from the ground up. Traditional back-end languages like PHP, Ruby, and Java were general-purpose languages adapted for the web. When they made a database call or read a file, they’d block and wait for the response before doing anything else. Node.js was designed around non-blocking I/O, meaning it can handle other work while waiting for slow operations to complete. This made it particularly well-suited for building fast, scalable network applications.

Node.js also ships with NPM, the package manager that gives you access to hundreds of thousands of JavaScript packages. When people talk about the JavaScript ecosystem, Node.js is the foundation most of it is built on.

I remember watching Ryan Dahl’s videos when Node.js first came out. The excitement was real. The promise of a single language that worked well on both the front-end and back-end was compelling. It streamlined existing workflows and lowered the bar for new developers who no longer had to learn a completely separate language just to build a server.