Why is everyone going crazy over WebAssembly?

The history of web has seen a few major events in the past three decades. One of them was the launch of JavaScript 22 years ago on December 4, 1995.  Since then JavaScript has slowly evolved to become the de-facto standard of front-end web development. The present day web is much more dynamic and data intensive. Heavy graphics based games and applications require a much more robust browser.  That is why developers are going crazy over the concept of WebAssembly. Is it here to replace JavaScript? Or is it like any other hype that will fade away with time? The answer is neither of the two.

Why use WebAssembly when you have JavaScript?

To understand the buzz around WebAssembly, we will have to understand what JavaScript does best and what its limitations are. JavaScript compiles into machine code as it runs in the browser. Machine code is the language that communicates with the PC and instructs it what to do. Not only that, it also parses, analyzes, and optimizes the Emscripten-generated JavaScript while loading the application. That’s what makes the browser slow in compute heavy applications.

JavaScript is a dynamically typed language. It doesn’t have any stored functions in advance. That’s why when the compiler in your browser runs JavaScript, it doesn’t know which function call is going to come next. That might seem very inconvenient. But that feature is what makes JavaScript based browsers so intuitive, and interactive. This feature ensures that your system would not have to install a standalone desktop application. The same application can be run from the browser.

Graphical Representation of an Assembler-Source: logrocket

The above image shows how an assembly level language is transformed into machine code when it is compiled. This is what exactly happens when WebAssembly code runs in browser. But since WebAssembly is in binary format, it becomes much easier for the compiler to convert it into machine code.

Unfortunately JavaScript is not suitable for every single application. For example, gaming is an area, where running JavaScript code in the browser for a highly interactive multiplayer game is not the best solution. It takes a heavy toll on the system resources. That’s where WebAssembly comes in.

1. WebAssembly is a low level binary language that runs parallel to JavaScript. Its biggest advantages are speed, portability and flexibility.

The speed comes from the fact that Webassembly is in binary. JavaScript is a high level language. Compiling that to the machine code puts significant pressure on the JavaScript engine. Compared to that, WebAssembly binary files are much smaller in size (in Kb) and easy to execute and convert to machine code.



Functioning of a WASM: Source: logrocket

The code optimization in WebAssembly happens during the compilation of source code, unlike JavaScript. WebAssembly manages memory manually, just like in languages like C and C++, so there’s no garbage collection either. This enables code compiler performance similar to native code. You can also compile other languages like Rust, C, C++ into WASM format. This enables developers to run their native code in the browser without knowing much of JavaScript.

WASM is not something that you can write as a code. It’s a format which is created from your native code, that transcompiles directly into machine code. This allows it to run parallel to HTML5, CSS and JavaScript code, giving you the taste of both worlds.

So, is WebAssembly going to replace JavaScript?

JavaScript is clearly not replaceable. Just that for heavy graphics/ audio/ AI based apps, a lot of function calls are made in the browser. This makes the browser slow. WebAssembly eases out this aspect. There are separate compilers that can turn your C, C++, Rust code into WASM code. These are then used in the browser as JavaScript objects. Since these are very small in size, they make the application fast.

Support for WebAssembly has been rolled out by all major browsers. Majority of the world is using WebAssembly currently in their browsers. Until JavaScript capabilities improve, WebAssembly will work alongside Javascript to make your apps perform better and in making your browser interactive, intuitive and lightweight.



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