Edge Computing with Cloudflare Workers & Deno · 课时

Deno 运行时基础

探索 Deno 的核心功能和内置工具，并了解它与 Node.js 的区别。

Deno 运行时基础 是 CoddyKit 上的免费 Edge Computing with Cloudflare Workers & Deno 课时。这是第 1 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 Edge Computing with Cloudflare Workers & Deno 学习路径的一部分，你的进度在网页和 CoddyKit 应用中同步。 Edge Computing with Cloudflare Workers & Deno 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。

Welcome to Deno Essentials

Welcome! In this lesson, we'll dive into Deno, a modern, secure runtime for JavaScript and TypeScript.

Created by Ryan Dahl (who also created Node.js), Deno addresses some of the design choices made in Node.js, focusing on security and a great developer experience.

Security First: Deno's Approach

One of Deno's biggest differences is its security model. By default, Deno scripts run in a sandbox, meaning they have no access to:

The file system
The network
Environment variables
Subprocesses

You must explicitly grant these permissions using command-line flags. This prevents malicious code from doing harm without your knowledge.

Built-in Tooling

Deno comes with a powerful set of built-in tools. Forget installing separate packages for formatting, linting, or testing!

Key tools include:

deno fmt: Code formatter
deno lint: Linter for code quality
deno test: Test runner
deno doc: Documentation generator
deno compile: Compiles scripts into self-contained executables

This integrated experience simplifies project setup and maintenance.

Native TypeScript Support

Deno supports TypeScript out of the box. This means you can write TypeScript code without needing a separate compilation step or tsconfig.json file.

It also embraces ES Modules, allowing you to import modules directly from URLs, much like how browsers work. No more node_modules folder!

Your First Deno Program

Let's write a simple Deno program. Save this as hello.ts (or .js) and run it with deno run hello.ts.

console.log("Hello from Deno!");
console.log("Deno is awesome.");

Deno vs. Node.js: Core Differences

While both Deno and Node.js are JavaScript runtimes, they have fundamental differences:

Security: Deno is secure by default (permissions needed), Node.js has full access.
TypeScript: Deno supports TS natively, Node.js requires transpilation.
Tooling: Deno has built-in tools (fmt, lint, test), Node.js relies on npm packages.
Module System: Deno uses URL-based ES Modules, Node.js uses CommonJS (though ES Modules are gaining traction).
Standard Library: Deno has a robust standard library, Node.js has a smaller core.

The Global Deno Object

Deno exposes a global Deno object that provides access to runtime-specific APIs, like file system operations, network access, and environment variables.

Here's how you can access command-line arguments passed to your script:

console.log("Arguments:", Deno.args);

// Try running: deno run my_script.ts arg1 arg2

Running with Permissions

To demonstrate Deno's permission model, let's try to read a file. This script will fail without explicit permission.

To run it successfully, you'll need to add the --allow-read flag: deno run --allow-read file_reader.ts

try {
  const content = Deno.readTextFileSync("data.txt");
  console.log("File content:\n" + content);
} catch (error) {
  console.error("Error reading file: ", error.message);
  console.error("Hint: Try 'deno run --allow-read file_reader.ts'");
}

Deno Essentials Check

Which of the following statements about Deno is TRUE?

Recap: Deno's Foundation

Great job! In this lesson, you've learned about Deno's foundational features:

Its security-first approach with a granular permission model.
The convenience of its built-in tooling.
Native TypeScript and ES Module support.
The global Deno object for runtime interactions.

These essentials make Deno a powerful and modern runtime for web development, especially at the edge!

常见问题解答

「Deno 运行时基础」课时是免费的吗？

是的 — 「Deno 运行时基础」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 Edge Computing with Cloudflare Workers & Deno 课程的其余内容，请升级到 CoddyKit PRO。 Edge Computing with Cloudflare Workers & Deno 课程共包含 4 节课。

「Deno 运行时基础」这节课中我会学到什么？

探索 Deno 的核心功能和内置工具，并了解它与 Node.js 的区别。你通过在浏览器中直接运行的动手代码来练习 Edge Computing with Cloudflare Workers & Deno，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 Edge Computing with Cloudflare Workers & Deno 需要有经验吗？

无需任何先前经验。CoddyKit 上的 Edge Computing with Cloudflare Workers & Deno 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 1 节课，共 4 节。

「Deno 运行时基础」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 Edge Computing with Cloudflare Workers & Deno 课中编写并运行代码吗？

能。每节 Edge Computing with Cloudflare Workers & Deno 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。

此课程中的所有课时

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