WebAssembly vs JavaScript

When discussing the web, the foundation of the web or how websites and applications can connect via the internet there are different aspects of it, such as web technologies, client-server model architecture which determines how the web works, the internet infrastructure such as DNS (Domain Name System), Web communication protocols like HTTP/HTTPS, Security and Encryption, databases, and so on.

In this article, we’ll discuss and compare two core web technologies, namely WebAssembly and JavaScript, examining how they relate and differ, and how they both make using the web possible.

TL; DR:

WebAssembly makes it possible to run languages like C++, and Rust on the web. It was created to handle high computational task efficiently and can also run independently as a runtime not just in the browser. While JavaScript was built specifically for the web but extends beyond the web as it is used for both the front end, backend, mobile and desktop applications.

Web Assembly

WebAssembly, or Wasm, is a low-level assembly-like language that can be run in modern web browsers. It was created as a solution to handling computational tasks that JavaScript isn’t able to, and enables languages like C, C++, C#, and Rust to be compiled into WebAssembly bytecode that modern browsers can execute. 

WebAssembly code is in a binary format, which makes it more compact, allowing it to load and execute faster than JavaScript. 

Why was WebAssembly Created?

WebAssembly was designed to work alongside JavaScript to handle high-performance, computation-intensive tasks. 

JavaScript is a scripting language written in plain text that has to be compiled and goes through several stages, like tokenization, parsing, and execution, every time it runs, which can slow down performance in browsers.  

Compared to JavaScript, WebAssembly is a binary, statically typed language that the CPU can understand directly. When the browser loads WebAssembly code, it compiles it to native machine code. Because WebAssembly code is compact and precompiled, execution is much faster.  

The core purpose of WebAssembly includes the following; 

Speed and Efficiency: WebAssembly code uses the capabilities of being a low-level language that uses binary instructions and the browser engine to enable speed of code execution across different platforms on the web or outside the web.

It executes at near-native speed, which improves performance significantly, suitable for games and high computational tasks.

Portability: WebAssembly enables code written in languages like C, C++, and Rust to run across modern web browsers and operating systems. For example, when a C++ program is compiled to WebAssembly, the file can run in multiple browsers and on different operating systems without modification, ensuring cross-platform compatibility. 

Security: WebAssembly runs in a safe sandboxed environment. It adheres to the browser’s same-origin and permission policies, ensuring code executes safely. 

The previous version of WebAssembly (Wasm 2.0) has certain benefits according to experts, such as;

128-Bit SIMD Operation:  WebAssembly 2.0 supports SIMD functionality(128-bit) to speed up computationally intensive tasks like video processing, machine learning, and 3D rendering. 

Multi-Value Returns: Functions return multiple values, improving flexibility and simplifying logic flows.

Bulk Memory Operations: Memory copying and initialization are faster and easier.

Non-trapping conversions and Sign Extension: This adds safety and efficiency to numeric operations.

Reference Types: Modules can interact directly with external objects like JavaScript functions or DOM elements 

However, according to experts, it still faces a lack in areas like; 

SIMD Support: This still requires or demands low-level expertise, and it has uneven browser support.

Bulk Memory Operation: Adds more complexity for developers without knowledge of memory layout. 

Non-trapping conversion and sign extension: Beneficial to low-level logic and has a minor impact on high-level applications. 

Reference types: Often require glue code for external objects, which can limit usability in front-end heavy projects. 

Some other limitations of WebAssembly include; 

Lack of Direct DOM Access: Modules require JavaScript to interact with the DOM

Limited Debugging Tools: Debugging is more challenging compared to JavaScript.

Dependence on JavaScript Bridges: Interoperability with APIs may require additional JavaScript code, which can make the frontend bulky.

Limited Adoption: WebAssembly is not widely adopted for general front-end development.

Where WebAssembly can be Applied

WebAssembly can be applied in areas like:

Browser-based AI: Wasm can quicken the execution of AI models in the browser, improving performance for intensive tasks like machine learning inference and pre-processing. 

Real-time Media App: Wasm can be used to deliver a fast and responsive user experience during tasks like audio and video processing. 

Edge computing: Wasm is portable, secure, and it's fast; execution makes it ideal for running logic closer to users, where low-latency responses are critical.

Games and Simulation: WebAssembly is great for running games and simulations because it is designed to handle heavy computational tasks efficiently.

WebAssembly upgrades

WebAssembly has evolved from just helping JavaScript run applications faster to becoming a runtime, and with the current update on Wasm 3.0, it has completed the development of major features such as;

Memory 63: WebAssembly memory was limited to 32-bit addresses, meaning a cap of 4 gigabytes, which was fine for web browsers but limited for non-web environments.  Web Assembly now supports 64-bit addressing, which gives access to 16 exabytes of memory, which wouldn't be used with hardware that much, but it's great for standalone Wasm engines. This is great for handling massive workloads. 

Multi-Memory: Multi-Memory is supported in a single module; you can declare and access multiple memory spaces in one place, unlike before, where you had to split memories across modules if you needed more than one memory space. 

Garbage Collection: Wasm introduces support for managed memory through a built-in garbage collector at a low level.  This allows languages that compile to WebAssembly to represent structured data and handle memory management efficiently.

Tail Call Optimization: WebAssembly supports tail call for statically defined functions and dynamic calls through tables of references.

Exception Handling: Exceptions are native; you can declare exceptions with payload and use Wasm instructions to throw and catch them.

With the latest updates, the browser can now run complex programming languages directly without relying on JavaScript as support.

JavaScript

JavaScript is a programming language that makes it possible to make websites interactive, add logic, and create real-time behaviour in web pages; this means that users can interact with elements on the web page. 

Websites used to be static with just a bit of text and a little pop of colour, but JavaScript makes it possible to add animations and interactivity. Apart from that, it can be used to build both front-end and back-end applications. It is also what created a foundation for frameworks like React, Vue, and it is the most widely used language, very approachable with a simple learning curve.

Features of JavaScript 

Wider Adoption: JavaScript is a popular language that has a large ecosystem, frameworks, and tools that help developers build dynamic web applications. It also has extensive support and can be used to build both small and large web applications.

Document Object Model Manipulation:  JavaScript can manipulate the DOM and update dynamic content without refreshing the page. This direct access to the DOM not only improves user experience by making pages responsive to users' actions but is great for interactive features like form validation and content updates.

Rapid Prototyping: JavaScript can run directly in the browser without compiling, which promotes rapid prototyping and the ability to see code changes immediately. This makes it easy for developers to test functionality and see how elements interact in real time, making adjustments and implementing faster, which can accelerate development time. 

Server-Side Implementation: JavaScript is used for both client-side and server-side applications, and it is not only used in the browser, thanks to Node.js, which makes it possible to run JavaScript on servers.

Adaptive Nature: It was created for the browser, but it can be used on servers, desktop apps, and mobile applications. It also supports dynamic typing, which means that variables do not require a fixed type. Also, it continually evolves to meet modern development, and it can work alongside other technologies like WebAssembly for tasks that require heavy computation.

WebAssembly vs. JavaScript

Summary

WebAssembly promises to improve the capabilities of building on the web, and one of the core features that was hyped during its release is its portability, which enables cross-platform compatibility. It can power production systems in high-performance use cases, and run independently as a standalone runtime, making it more than just a web tool. It can also run-on servers or devices.

JavaScript, on the other hand, remains a great choice for building web applications. It runs in both browser and server environments, is highly flexible, and enables the creation of interactive and dynamic UI interfaces. 

Frequently Asked Questions