WebAssembly vs. JavaScript: What’s the Difference?

In the world of computing, Javascript and WebAssembly are relatively new technologies, but they’re quickly gaining popularity. Each of these has its strengths and weaknesses, but the one you choose will depend on your specific project requirements, as well as what part of the development process you’re working on (e.g., development or deployment). Let’s take a look at both Javascript and WebAssembly to get an idea of where each excels and where each falls short.

What is WebAssembly?

WebAssembly (WASM), short for Web Assembly Language, is a binary format for writing programs that run in web browsers. WASM was designed to allow developers to write code once and have it work across any platform that supports JavaScript.


WASM is currently supported by major browsers including Chrome, Firefox, Edge, Safari, Opera, and Microsoft Internet Explorer. Unlike other web languages such as JSX or Typescript, you can use any text editor to create or edit WASM files because they simply text files with .wasm extensions. For example, to save a file called my program. wasm using the nano text editor on Linux, you would enter the following command: $nano my program. wasm

What is Javascript?

Javascript is a programming language created by Netscape Communications Corporation in 1995. It is a general purpose, interpreted, dynamic scripting language. Its syntax is similar to C/C++ and Java. Javascript is commonly used in websites and web applications.


It is also used as an embedded component in other programs and platforms such as Adobe Flash Player or Microsoft Silverlight. JS code can be executed on the server side through Node.js, which allows users to build fast and scalable network applications easily with JavaScript’s event-driven architecture.

Key Differences in Performance

When it comes to performance, there are a few key differences between WebAssembly and Javascript.

  • First, WebAssembly is faster than Javascript because it is a compiled language. This means that it doesn’t have to be interpreted each time it runs, which can make a big difference in speed.
  • Second, WebAssembly is more memory-efficient than Javascript because it doesn’t have to keep track of as much information. This can be important for large applications that need to run quickly and smoothly.

Stronger Security and Reduced Vulnerabilities

When it comes to security, WebAssembly is leagues ahead of JavaScript. That’s because code written in WebAssembly is compiled into a binary format that is not human-readable. This makes it much more difficult for would-be attackers to reverse engineer your code and find vulnerabilities. It also means you can’t inadvertently open up your web app to attacks by including malicious scripts.

The way WebAssembly handles memory and resources also provides an extra layer of protection.

Wide Adoption From Major Players

Microsoft, Google, and Mozilla all announced plans to support WebAssembly in their browsers in early 2017. This means that WebAssembly has widespread support from major players in the web browser market. This is a big deal because it means that WebAssembly can be used to create applications that run in the browser with near-native performance.

It also means that developers will no longer have to write applications using other languages like C++ or Java, which would then need to be compiled into WebAssembly before they could be executed. Developers will now only need to write the code in JavaScript or another language of their choice, and still get near-native performance when running it on the web.

Better Performance in Mobile Browsers

One of the key benefits of WebAssembly is that it offers better performance in mobile browsers. This is because WebAssembly is a low-level language that is designed to be more efficient than higher-level languages like JavaScript.

In addition, WebAssembly is faster to decode and compile than JavaScript, which also contributes to its improved performance. However, even though WebAssembly provides an improvement over JavaScript when it comes to performance on mobile devices, it still doesn’t provide as much of an improvement as native code does.

Interoperability with other Languages

One of the key benefits of WebAssembly is that it is designed to be interoperable with other programming languages. This means that you can use WebAssembly alongside other languages to create more powerful applications. In contrast, Javascript is a single language that runs on web browsers. While it is possible to use other languages to create web applications, they will need to be compiled to Javascript for the browser to understand them. The result is an unnecessarily long development process.

Consequently, if we want to see the benefits of WebAssembly realized fully, we must first ensure that enough people are working on the project. If this happens, then developers will be able to leverage all their potential and create richer web apps with less effort.

Limitations in Processing Power/Functionality

While both WebAssembly and Javascript are programming languages that can be used to build web applications, there are some key differences between the two. WebAssembly is a low-level language that is designed to be more efficient than Javascript, which is why it is often used for applications that need to run quickly or process large amounts of data. However, this efficiency comes at a cost, as WebAssembly is more difficult to learn and use than Javascript.

Does Code Size Matter?

In the world of web development, there is always a debate over which programming language is better. Some people prefer WebAssembly because it offers a smaller code size, while others prefer Javascript because it is more widely used. So, does code size matter? The answer is not simple. If you are building an application that needs to be delivered quickly, then you might want to use WebAssembly because it provides faster load times.

However, if you are building an application that needs to work on many different platforms and with different languages (for example if your users may need to switch from English to Spanish), then you might want to use Javascript instead because it will be compatible with any device or system in any region around the world.


Though they may look similar at first glance, WebAssembly and Javascript are two very different technologies. WebAssembly is a low-level language that is designed to be faster and more efficient than Javascript, while Javascript is a high-level language that is easy to learn and use. In the end, it’s up to the developer to decide which technology is right for their project.

About James Smith

A freelance writer specializing in business, finance, and technology. He has studied these subjects and spends a lot of time developing content to assist explain complex content for the average individual.

View all posts by James Smith →