WebAssembly (WASM) for High Performance Apps · 课时

使用 Node.js 在服务端运行 WASM

将 WebAssembly 模块集成到 Node.js 应用中，实现高性能的服务端逻辑和微服务

使用 Node.js 在服务端运行 WASM 是 CoddyKit 上的免费 WebAssembly (WASM) for High Performance Apps 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 WebAssembly (WASM) for High Performance Apps 学习路径的一部分，你的进度在网页和 CoddyKit 应用中同步。 WebAssembly (WASM) for High Performance Apps 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。

Server WASM with Node.js

Welcome! In this lesson, we'll explore how WebAssembly (WASM) isn't just for browsers. We'll learn to integrate high-performance WASM modules directly into Node.js applications.

This allows you to leverage WASM's speed for server-side logic, microservices, and computationally intensive tasks.

Benefits of WASM on Server

Why bring WASM to the server?

Performance: Execute near-native code for demanding tasks.
Portability: Run the same WASM module across different server environments.
Security: WASM's sandboxed environment offers enhanced security for untrusted code.
Language Agnostic: Write high-performance logic in C, C++, Rust, Go, and more, then run it in Node.js.

Node.js's WASM Support

Node.js has built-in support for WebAssembly, making it straightforward to load and execute WASM modules. It provides the same WebAssembly global object available in browsers.

This means you can use familiar JavaScript APIs to interact with your compiled WASM code.

Our First C Module

Let's start with a very simple C function. We'll compile this C code into a WebAssembly module.

This function will just add two integers, demonstrating basic interaction.

int add_numbers(int a, int b) {
  return a + b;
}

Compiling C to WASM

To turn our C code into a WASM module, we use a toolchain like Emscripten. The command would look something like this:

emcc my_module.c -o my_module.wasm -s EXPORTED_FUNCTIONS="['_add_numbers']"

This creates my_module.wasm, which contains our compiled add_numbers function, ready for Node.js!

Loading WASM File

First, we need to read the .wasm file from our file system. Node.js's fs module is perfect for this.

Assume my_module.wasm is in the same directory.

const fs = require('fs');
const path = require('path');

async function loadWasm() {
  // In a real scenario, 'my_module.wasm' would be a compiled file.
  // For this runnable example, we use a dummy path.
  const wasmPath = path.resolve(__dirname, 'dummy.wasm'); 
  
  try {
    const bytes = await fs.promises.readFile(wasmPath); 
    console.log('WASM bytes loaded! (if file existed)');
  } catch (error) {
    console.log('Dummy WASM file not found, proceeding...');
  }
}

loadWasm();

Instantiating the Module

Once we have the WASM bytes, we use WebAssembly.instantiate() to compile and instantiate the module. This gives us an instance object with access to exported functions.

For a runnable example, we'll use a very small, self-contained WASM binary that adds two numbers.

const fs = require('fs');

async function loadAndInstantiateWasm() {
  // A minimal WASM binary for 'add(a, b) => a + b'
  const wasmCode = new Uint8Array([
    0x00, 0x61, 0x73, 0x6d, 0x01, 0x00, 0x00, 0x00, // WASM magic and version
    0x01, 0x07, 0x01, 0x60, 0x02, 0x7f, 0x7f, 0x01, 0x7f, // Type section: func(i32, i32) -> i32
    0x03, 0x02, 0x01, 0x00, // Function section: one function, type 0
    0x07, 0x07, 0x01, 0x03, 0x61, 0x64, 0x64, 0x00, 0x00, // Export section: export 'add' as func 0
    0x0a, 0x09, 0x01, 0x07, 0x00, 0x20, 0x00, 0x20, 0x01, 0x6a, 0x0b // Code section: get_local 0, get_local 1, i32.add
  ]);

  const { instance } = await WebAssembly.instantiate(wasmCode);
  console.log('WASM module instantiated!');
  // The 'instance' now holds our exported functions.
}

loadAndInstantiateWasm();

Calling Exported Functions

Now that our WASM module is instantiated, we can access its exported functions through instance.exports. Our WASM module exports an add function.

Let's call it and see the result!

const fs = require('fs');

async function callWasmFunction() {
  // A minimal WASM binary for 'add(a, b) => a + b'
  const wasmCode = new Uint8Array([
    0x00, 0x61, 0x73, 0x6d, 0x01, 0x00, 0x00, 0x00, // WASM magic and version
    0x01, 0x07, 0x01, 0x60, 0x02, 0x7f, 0x7f, 0x01, 0x7f, // Type section: func(i32, i32) -> i32
    0x03, 0x02, 0x01, 0x00, // Function section: one function, type 0
    0x07, 0x07, 0x01, 0x03, 0x61, 0x64, 0x64, 0x00, 0x00, // Export section: export 'add' as func 0
    0x0a, 0x09, 0x01, 0x07, 0x00, 0x20, 0x00, 0x20, 0x01, 0x6a, 0x0b // Code section: get_local 0, get_local 1, i32.add
  ]);

  const { instance } = await WebAssembly.instantiate(wasmCode);
  const result = instance.exports.add(10, 20); // Calling the 'add' function
  console.log('Result from WASM:', result);
}

callWasmFunction();

Passing Primitive Data

As shown, passing primitive data types like integers (i32) between Node.js (JavaScript) and WASM is straightforward. WASM modules often use i32 for integers and f32/f64 for floats.

JavaScript numbers are 64-bit floats, but they are implicitly converted when passed to WASM functions expecting integer types.

WASM in Node.js Check

You've learned how to load and interact with a WASM module in Node.js. Let's test your understanding.

Server-Side WASM Recap

Great job! You've learned how to integrate WebAssembly modules into Node.js applications.

WASM brings high performance and portability to server-side logic.
Node.js provides native APIs (WebAssembly.instantiate) for loading and running WASM.
You can compile code from languages like C/C++ to WASM using tools like Emscripten.
Interacting with WASM functions and passing primitive data is direct and efficient.

This opens up exciting possibilities for building performant and flexible server applications!

常见问题解答

「使用 Node.js 在服务端运行 WASM」课时是免费的吗？

是的 — 「使用 Node.js 在服务端运行 WASM」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 WebAssembly (WASM) for High Performance Apps 课程的其余内容，请升级到 CoddyKit PRO。 WebAssembly (WASM) for High Performance Apps 课程共包含 4 节课。

「使用 Node.js 在服务端运行 WASM」这节课中我会学到什么？

将 WebAssembly 模块集成到 Node.js 应用中，实现高性能的服务端逻辑和微服务你通过在浏览器中直接运行的动手代码来练习 WebAssembly (WASM) for High Performance Apps，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 WebAssembly (WASM) for High Performance Apps 需要有经验吗？

无需任何先前经验。CoddyKit 上的 WebAssembly (WASM) for High Performance Apps 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。

「使用 Node.js 在服务端运行 WASM」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 WebAssembly (WASM) for High Performance Apps 课中编写并运行代码吗？

能。每节 WebAssembly (WASM) for High Performance Apps 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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