Getting Started with Web Assembly: A Step-by-Step Guide

Are you tired of slow and inefficient JavaScript code? Do you want to speed up your web application? Look no further than Web Assembly! In this tutorial, we will walk you through the process of setting up and using Web Assembly in your web development projects.

What is Web Assembly?

Web Assembly is a low-level binary format that allows you to run code written in languages other than JavaScript in a web browser. This means you can write code in languages such as C, C++, and Rust and have it run in the browser just like JavaScript. Web Assembly code is faster and more efficient than JavaScript, making it ideal for CPU-intensive tasks such as video encoding or machine learning.

Setting up your Environment

Before we can start using Web Assembly, we need to set up our environment. First, we need to install the Emscripten toolchain. Emscripten is a set of tools that allows you to compile C and C++ code to Web Assembly. Installation instructions for Emscripten can be found here.

Once you have installed Emscripten, we need to create a test file. Create a new file called test.c and add the following code:

#include <stdio.h>

int main() {
  printf("Hello, World!");

Save the file and navigate to the folder where the file is located using your terminal. Run the following command:

emcc test.c -o test.js

This will compile the test.c file into a JavaScript file called test.js.

Using Web Assembly in your Web Application

Now that we have a basic understanding of what Web Assembly is and have set up our development environment, let's walk through the steps to use Web Assembly in a web application.

Step 1: Create a Web Page

Create a new HTML file called index.html and add the following code:

<!DOCTYPE html>

  <meta charset="utf-8">
  <title>Web Assembly Example</title>

  <script src="main.js"></script>


This is a basic HTML file that includes a script tag for main.js, which we will create in the next step.

Step 2: Create a JavaScript file

Create a new JavaScript file called main.js and add the following code:

const importObject = {
  imports: { imported_func: arg => console.log(arg) }

WebAssembly.instantiateStreaming(fetch('test.wasm'), importObject)
  .then(obj => obj.instance.exports.exported_func());

This code creates an importObject that defines the imported function imported_func, which takes an argument and logs it to the console. It then uses the WebAssembly.instantiateStreaming() method to load and compile the test.wasm file and create an instance of the Web Assembly module. It then calls the exported function exported_func(), which will call imported_func() with the argument "Hello, World!".

Step 3: Compile the C file to Web Assembly

In step one, we compiled the test.c file to a JavaScript file called test.js. However, we want to compile it to a Web Assembly file called test.wasm. To do this, run the following command:

emcc test.c -s WASM=1 -o test.wasm

This will compile the test.c file into a Web Assembly file called test.wasm.

Step 4: Serve the Web Page

Finally, we need to serve our web page. There are many ways to serve a web page, but a quick and easy way to do this is to use the python HTTP server.

Open a new terminal window and navigate to the folder where your index.html file is located. Run the following command:

python -m http.server

This will start a local HTTP server on port 8000. Open your web browser and navigate to http://localhost:8000. You should see the message "Hello, World!" logged to the console.


Congratulations! You have successfully set up and used Web Assembly in a web application. This tutorial is just the beginning of what is possible with Web Assembly. Be sure to check out the Web Assembly official documentation for more information and resources.

We hope you found this tutorial helpful and informative. Please share your thoughts and experiences in the comments below. Thanks for reading!

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