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Dharan Ganesan
Dharan Ganesan

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Day 91: WebAssembly

What is WebAssembly?

WebAssembly is a binary instruction format that serves as a portable compilation target for programming languages, allowing them to run at near-native speed in web browsers. The WebAssembly API provides a set of JavaScript interfaces for interacting with WebAssembly modules.

Key Concepts:

  • Module: Represents a compiled Wasm module, containing functions and other elements.
  • Instance: An instantiation of a Wasm module, allowing you to execute its functions and access its memory.
  • Memory: WebAssembly has its own linear memory, managed by an ArrayBuffer.

Setting Up the C++ Game 🎮

Let's start with a basic C++ game file (game.cpp):

// game.cpp
#include <iostream>

extern "C" {
    void playGame() {
        std::cout << "Playing the C++ game!\n";
        // Your game logic goes here
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Compile this C++ code to WebAssembly using Emscripten:

em++ game.cpp -o game.wasm -s WASM=1 -s EXPORTED_FUNCTIONS="['_playGame']"
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The -s EXPORTED_FUNCTIONS flag ensures that the playGame function is accessible from JavaScript.

Now, let's write the JavaScript code to load and run the C++ game using the WebAssembly API:

// Load and run a C++ game compiled to WebAssembly
async function loadAndRunGame() {
  // Assuming the compiled WebAssembly file is named game.wasm
  const response = await fetch('game.wasm');
  const bytes = await response.arrayBuffer();
  const { instance } = await WebAssembly.instantiate(bytes, {
    env: {
      // If your C++ code uses functions like console.log, you might need to provide implementations here

  // Run the playGame function from C++

// Load and run the C++ game
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Replace 'game.wasm' with the actual name of your compiled WebAssembly file. If your C++ code relies on functions like console.log or other environment-specific features, provide appropriate implementations in the env object during instantiation.

Tips 💡

1. Optimize Module Size:

  • Minimize the size of your Wasm modules by using compiler flags and optimizations.
  • Consider using tools like wasm-opt to further reduce module size.

2. Memory Management:

  • Understand and manage WebAssembly memory efficiently using WebAssembly.Memory.
  • Use typed arrays for efficient data transfer between JavaScript and WebAssembly.

3. Debugging:

  • Leverage browser developer tools for debugging both JavaScript and WebAssembly code.
  • Utilize tools like wabt for debugging Wasm modules directly.

Use Cases 🌐

1. Gaming:

Integrate complex game logic and physics engines written in languages like C++ into web-based games for optimal performance.

2. Image and Video Processing:

Perform resource-intensive image and video processing tasks, such as filters and transformations, with the speed of compiled languages.

3. Cryptography:

Implement cryptographic algorithms in WebAssembly to enhance security without sacrificing performance.

4. Computational Libraries:

Use existing C/C++ libraries for mathematical computations or simulations seamlessly in web applications.

5. Augmented Reality:

Bring immersive augmented reality experiences to the web by leveraging the speed and efficiency of WebAssembly.

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Dharan Ganesan