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WebAssembly, Javascript

WebAssembly, Javascript

Comparing WebAssembly and JavaScript: Key Differences and Use Cases

Apr 2, 2023

Apr 2, 2023

In this article, we delve into the differences between WebAssembly and JavaScript, highlighting their respective strengths and use cases. Discover how these two technologies can work together to create highly performant web applications that leverage the best of both worlds.

WebAssembly (Wasm) and JavaScript are both essential technologies in modern web development. While JavaScript has been the de facto language for web development for over two decades, WebAssembly is a relatively new technology that aims to improve web performance and enable new use cases. In this article, we'll dive deep into the key differences between WebAssembly and JavaScript, their use cases, and how they can be used together to build powerful web applications.


JavaScript is a high-level, interpreted programming language primarily used for client-side web development. It enables dynamic content, interactivity, and complex features on web pages. Since its inception in 1995, JavaScript has evolved into a versatile language capable of handling server-side programming, mobile app development, and even desktop applications.

WebAssembly is a low-level, binary instruction format designed as a portable target for the compilation of high-level languages like C, C++, and Rust. Introduced in 2015, it enables near-native performance and allows developers to leverage languages other than JavaScript for web development. WebAssembly runs alongside JavaScript, enabling developers to create high-performance web applications with a broader set of languages.

Key Differences


JavaScript is an interpreted language, which means that it has to be parsed and executed by the browser at runtime. While modern JavaScript engines have made significant optimizations, JavaScript's performance can still be a bottleneck, especially for computationally intensive tasks.

WebAssembly, on the other hand, is designed for near-native performance. Its binary format allows for faster parsing and execution compared to JavaScript. Additionally, WebAssembly's low-level nature provides better control over memory management, resulting in improved performance for compute-heavy tasks.

Language Support

JavaScript has been the only language natively supported by browsers for many years. However, with the advent of WebAssembly, developers can now write web applications using languages like C, C++, and Rust, among others. This opens the door for code reuse, leveraging existing libraries, and utilizing the strengths of other languages for specific tasks.


Both JavaScript and WebAssembly run inside a sandboxed environment, providing isolation from the host system. However, WebAssembly's low-level nature allows for more granular control over memory management, which can lead to better security practices in certain scenarios.

Use Cases


JavaScript shines in areas where it has traditionally been used, such as:

  • DOM manipulation and user interface updates

  • Event handling and asynchronous operations

  • Simple animations and effects

  • Form validation and user input processing

  • Building and consuming APIs

JavaScript also benefits from a vast ecosystem, numerous libraries and frameworks, and a large developer community.


WebAssembly is ideal for use cases that require high-performance computing or where developers prefer to use languages other than JavaScript. Some examples include:

  • Graphics-intensive applications, such as games and 3D rendering

  • Audio and video processing

  • Image recognition and computer vision

  • Scientific simulations and complex calculations

  • Cryptography and data compression

Combining WebAssembly and JavaScript

WebAssembly and JavaScript can work together in the same application, each handling the tasks they excel at. For instance, JavaScript can be used for UI updates, event handling, and API calls, while WebAssembly handles compute-intensive operations. This combination allows developers to build highly performant web applications that leverage the best of both technologies.