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Web Assembly using JavaScript (Wasm)

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2023-09-01 23:49:061329browse

使用 JavaScript 的 Web 组装 (Wasm)

Have you ever wondered whether you could run high-performance applications on the web without sacrificing the portability and security provided by JavaScript? Well, wonder no more! With the introduction of WebAssembly (Wasm), it is now possible to bring native-like performance to web applications while still leveraging the power of JavaScript. In this article, we’ll explore the basics of WebAssembly and how to use it with JavaScript to unlock a new world of possibilities.

What is WebAssembly (Wasm)?

WebAssembly, commonly known as Wasm, is a binary instruction format designed for web browsers. It is a low-level virtual machine capable of executing code at near-native speed. Wasm is the result of a collaboration between major browser vendors including Mozilla, Google, Microsoft, and Apple, with the goal of bringing high-performance applications to the web.

One of the main advantages of WebAssembly is that it is compatible with multiple programming languages, making it a universal solution for web development. You can write code in languages ​​like C, Rust, or even TypeScript, and then compile it into a Wasm binary format that can be executed directly in the browser.

Integrating WebAssembly with JavaScript

WebAssembly brings many benefits to web development. It allows developers to perform compute-intensive tasks at near-native speeds, making it suitable for applications that require high-performance execution. By leveraging WebAssembly, developers can port existing code bases written in languages ​​like C, Rust, or TypeScript to the web without sacrificing performance.

WebAssembly integration with JavaScript enables seamless interaction between the two languages. JavaScript acts as a bridge, providing a convenient interface for working with WebAssembly modules. This allows developers to combine the power of WebAssembly with the rich ecosystem and flexibility of JavaScript libraries and frameworks.

Although WebAssembly is a standalone technology, it integrates seamlessly with JavaScript, allowing developers to combine the benefits of both languages ​​in a single application. JavaScript acts as the glue between the web platform and WebAssembly modules, providing a convenient interface for interacting with compiled code.

JavaScript provides the API required to load WebAssembly modules. The fetch API is used to retrieve the binary file and pass the resulting ArrayBuffer to the WebAssembly.instantiate function. This function compiles the module asynchronously and returns an instance containing the exported functions and module memory. By accessing these exported functions, JavaScript can call functionality provided by the WebAssembly module.

To demonstrate this integration, let's consider a simple example. We will write a Wasm module that calculates the Fibonacci sequence and then call the module from JavaScript.

Step 1: Write the WebAssembly module

Let us first write the Fibonacci calculation logic in C. Save the following code in a file called fibonacci.cpp -

#include <emscripten.h>

extern "C" {
   int EMSCRIPTEN_KEEPALIVE fibonacci(int n) {
      if (n <= 1) {
         return n;
      } else {
         return fibonacci(n - 1) + fibonacci(n - 2);
      }
   }
}

illustrate

In this code, we have a C function fibonacci that recursively calculates the Fibonacci sequence. The EMSCRIPTEN_KEEPALIVE macro ensures that the function is exported and accessible from JavaScript.

Step 2: Compile the WebAssembly module

To compile C code to WebAssembly, we will use the Emscripten toolchain. Run the following command in terminal -

emcc fibonacci.cpp -s WASM=1 -o fibonacci.wasm

This command will generate the fibonacci.wasm file, which contains the compiled WebAssembly module.

Step 3: Call WebAssembly from JavaScript

Now that we have the WebAssembly module, let's call it from JavaScript. Save the following code in the HTML file index.html -

Example

<!DOCTYPE html>
<html>
<head>
   <script>
      const fetchAndInstantiate = async () => {
         const response = await fetch('fibonacci.wasm');
         const buffer = await response.arrayBuffer();
         const module = await WebAssembly.instantiate(buffer);
         const instance = module.instance;

         const fibonacci = instance.exports.fibonacci;
         const result = fibonacci(10);

         console.log('Fibonacci(10):', result);
      };

      fetchAndInstantiate();
   </script>
</head>
<body>
</body>
</html>

illustrate

In this code, we use the fetch API to retrieve the fibonacci.wasm file and convert it into an ArrayBuffer. We then instantiate the WebAssembly module using WebAssembly.instantiate and get the exported Fibonacci function from the module's instance. Finally, we call the Fibonacci function with parameter 10 and log the results to the console.

Step 4: Run the Example

To run the example, open the HTML file in a web browser. Open your browser's developer console and you should see the output Fibonacci(10): 55. This confirms that the WebAssembly module was successfully loaded and executed from JavaScript.

in conclusion

WebAssembly is a powerful technology that opens up new possibilities for high-performance web applications. By combining the benefits of WebAssembly and JavaScript, developers can leverage existing code bases, write performance-critical parts in lower-level languages, and integrate them seamlessly into their web projects. With the flexibility and portability of WebAssembly, the web platform promises to be a more powerful environment for running complex applications.

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