Node.js 与 NPM 入门

Node.js is a server-side JavaScript runtime — an engine that runs your JS outside the browser, right on a server or your own machine.

Why developers love Node.js: one language front to back, blazing V8 speed, non-blocking I/O for high concurrency, and the massive NPM ecosystem.

Node uses an event-driven, non-blocking model: it kicks off a task, registers a callback, and moves on — handling tons of connections without waiting around.

Check your setup with node -v. See a version number? You're good. If not, grab it from nodejs.org.

Let's write a classic Hello, World. Drop a console.log into a file named app.js — that's a full Node script.

Run it with node app.js from its folder. Node executes the script and prints your message to the terminal.

NPM (Node Package Manager) ships with Node and is the world's largest software registry. It installs third-party packages, shares your code, and tracks dependencies.

Start a project with npm init. It walks you through creating package.json — the file holding your project's metadata and dependency list.

Add a library with npm install express. NPM downloads it into node_modules and records it in your package.json.

Let's test your understanding of Node.js and NPM.

You've got the basics: Node.js runs JS on the server, and NPM manages packages via node, npm init, and npm install. Next: modules.