WebAssembly (WASM) is a high-performance, low-level binary format that allows code written in languages like C++, Rust, and Go to run in a web browser at near-native speed. It’s not a replacement for JavaScript, but a powerful partner designed to handle performance-critical, CPU-intensive tasks.
It’s a Partner, Not a Replacement for JavaScript 🤝
The most important thing to understand is that WebAssembly is designed to work alongside JavaScript, not replace it.
Analogy: The Interpreter and the Native Speaker 🗣️
- JavaScript is like a skilled, flexible interpreter. It’s great for most everyday tasks, managing the user interface, and handling dynamic events.
- WebAssembly is like a native speaker who has been given a highly optimized script to read. For raw speed on a specific, intensive task, the native speaker will always be faster.
You use JavaScript for the general-purpose logic of your application and call on WebAssembly modules to execute the heaviest computational parts at maximum speed.
How Does It Work?
The process is straightforward:
- Write Code: You write code for a performance-intensive task in a language like C++, Rust, or Go.
- Compile to WASM: You use a compiler (like Emscripten for C++) to turn your code into a compact, binary
.wasmfile. - Load in JavaScript: You load and instantiate the
.wasmmodule using a JavaScript API, which then gives you access to the compiled functions.
What Is It Used For Today?
WASM has unlocked a new class of powerful applications that can run directly in the browser.
- High-Performance Gaming: Game engines like Unity and Unreal Engine use WebAssembly to port complex, graphically-rich games to the web.
- In-Browser Creative Software: Companies like Adobe have used it to bring performance-heavy desktop applications like Photoshop and Premiere to the web.
- Video and Audio Processing: Real-time video editing, audio mixing, and video conferencing applications use WASM to handle the heavy processing tasks.
- Scientific Simulations: Running complex physics or data simulations that were previously too slow for the browser.
In short, WebAssembly breaks the performance barriers of traditional web technologies, making the browser a viable platform for almost any application.