WTF JavaScript tutorial helps newcomers get started with JavaScript quickly.

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Node.js or Node is an open source, cross-platform JavaScript runtime environment that allows JavaScript to run on the server outside of the browser environment. In this chapter, we'll cover the basics of Node.js, including how to install and use Node.js, and how to use npm (the Node package manager) to manage your project's dependencies.

First, you need to install Node.js on your computer. You can download the installation package corresponding to your operating system from the official website of Node.js (https://nodejs.org/zh-cn) and install it according to the prompts.

After the installation is complete, you can enter node -v on the command line to check your Node.js version:

$ node -v
v18.16.0

Node.js provides an interactive running environment called REPL (Read-Eval-Print Loop). In the REPL, you can enter and execute JavaScript code and view the results of the code execution.

To start the Node.js REPL, you just type node at the command line and start typing JavaScript code:

$node
> console.log('Hello, WTF Node.js!');
Hello, WTF Node.js!

In Node.js, every file is a module. You can import other modules using the require function and export modules using module.exports or exports:

//lib.js
module.exports = 'Hello, WTF Node.js!';

// app.js
let message = require('./lib');
console.log(message); // Output 'Hello, WTF Node.js!'

In the above example, we created two js files lib.js and app.js. You can enter node app.js on the command line and you will get the output 'Hello, WTF Node.js' !'.

npm is the default package manager for Node.js. You can use npm to install and manage your project's dependencies. Type npm -v on the command line to view your npm version:

$ npm -v
8.11.0

To create a new project using npm, you can use the npm init command. This command will guide you to create a package.json file, which is used to save the configuration and dependency information of your project.

To install a new dependency, you can use the npm install command:

$ npm install express

In this lecture, we introduced the basics of Node.js. Mastering Node.js, you can use JavaScript to create server-side applications/scripts, which will greatly expand your JavaScript programming capabilities.