Node.js Backend Development Bootcamp · 课时

详解 Node.js 模块系统

探索 CommonJS 模块和 ES 模块，了解如何在 Node.js 的不同文件之间导入和导出功能。

详解 Node.js 模块系统 是 CoddyKit 上的免费 Node.js Backend Development Bootcamp 课时。这是第 2 节课，共 4 节。你可以在下方免费阅读本课时的完整内容 — 然后在浏览器中使用内置代码编辑器和全天候 AI 导师进行实践。这是 Node.js Backend Development Bootcamp 学习路径的一部分，你的进度在网页和 CoddyKit 应用中同步。 Node.js Backend Development Bootcamp 课程共包含 4 节课。

本课时的部分内容尚未翻译，以英文显示。

Organize Your Code with Modules

As apps grow, one giant file gets messy. Modules split code into small, reusable, focused pieces. Node supports two systems: CommonJS and ES Modules.

CommonJS: `require()` & `module.exports`

CommonJS is Node's original module system: require() pulls code in, module.exports pushes code out. Import what you need, export what you offer.

CommonJS: Exporting a Function

Here's mathUtils.js. Whatever you assign to module.exports is what other files can import from it — here, just the add function.

const add = (a, b) => a + b;
const subtract = (a, b) => a - b;

module.exports = add; // Only 'add' is exported

CommonJS: Importing and Using

In another file, require('./mathUtils.js') pulls in that exported function. Keep both files in the same folder and run node app.js.

const addFunction = require('./mathUtils.js');

console.log("Using the imported function:");
console.log(`5 + 3 = ${addFunction(5, 3)}`);
console.log(`10 + 2 = ${addFunction(10, 2)}`);

CommonJS: Exporting Multiple Items

Need to export several things? Assign an object to module.exports holding all of them — a clean way to group related utilities.

const greet = (name) => `Hello, ${name}!`;
const farewell = (name) => `Goodbye, ${name}!`;

module.exports = {
  greetUser: greet,
  sayGoodbye: farewell
};

CommonJS: Importing Multiple Items

When a module exports an object, grab pieces with destructuring: const { greetUser, sayGoodbye } = require(...). Cleaner and clearer than dot access.

const { greetUser, sayGoodbye } = require('./utils.js');

console.log(greetUser('Alice'));
console.log(sayGoodbye('Bob'));

ES Modules: The Modern Standard

ES Modules (ESM) are JavaScript's official standard, using import/export. They enable tree-shaking — set "type": "module" or use .mjs to opt in.

ESM: Named Exports & Imports

With named exports, you export values by name and import them in matching { } braces — making it obvious exactly which parts you're using.

export const add = (a, b) => a + b;
export const multiply = (a, b) => a * b;

// app.mjs (main entry point)
// To run this: ensure package.json has "type": "module"
// and run with `node app.mjs`
import { add, multiply } from './calculator.mjs';

console.log(`2 + 4 = ${add(2, 4)}`);
console.log(`5 * 6 = ${multiply(5, 6)}`);

ESM: Default Exports

A module can have one default export, usually its main feature. Import it under any name you like, no braces needed.

const logMessage = (msg) => console.log(`[LOG] ${msg}`);
export default logMessage;

// main.mjs (main entry point)
// To run this: ensure package.json has "type": "module"
// and run with `node main.mjs`
import myLogger from './logger.mjs';

myLogger('This is a default message.');
myLogger('Another important event.');

Quick Check: Module Systems

You've learned about CommonJS and ES Modules. Let's test your understanding!

Recap: Node.js Modules

You've explored Node modules: CommonJS (require/module.exports, the classic) and ESM (import/export, the modern standard). Both keep apps organized.

常见问题解答

「详解 Node.js 模块系统」课时是免费的吗？

是的 — 「详解 Node.js 模块系统」的完整文本可在网页上免费阅读。要进行交互式练习（内置代码编辑器和全天候 AI 导师）并解锁 Node.js Backend Development Bootcamp 课程的其余内容，请升级到 CoddyKit PRO。 Node.js Backend Development Bootcamp 课程共包含 4 节课。

「详解 Node.js 模块系统」这节课中我会学到什么？

探索 CommonJS 模块和 ES 模块，了解如何在 Node.js 的不同文件之间导入和导出功能。你通过在浏览器中直接运行的动手代码来练习 Node.js Backend Development Bootcamp，全天候 AI 导师会在你学习这节课的过程中回答你的问题。

学习 Node.js Backend Development Bootcamp 需要有经验吗？

无需任何先前经验。CoddyKit 上的 Node.js Backend Development Bootcamp 课程适合初学者到高级学习者，你可以从这里开始或从头开始，按照自己的节奏学习。这是第 2 节课，共 4 节。

「详解 Node.js 模块系统」课时需要多长时间？

大多数 CoddyKit 课程大约需要 5–10 分钟。每节课都很精短且互动，所以你能稳步进步，并在网页和应用中从离开的地方继续。

我能在这节 Node.js Backend Development Bootcamp 课中编写并运行代码吗？

能。每节 Node.js Backend Development Bootcamp 课都包含内置代码编辑器，你可以在浏览器中直接编写并运行真实代码，并获得即时 AI 反馈 — 无需本地设置。

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