WebAssembly – Smart technology platform on the block

Since the last decade, JavaScript has been unable to ease the developer burden due to its dynamic nature. Furthermore, for applications in which performance is critical, Javascript is not fast enough. For areas in which significant engineering effort is required in another language, it may not make sense to convert to JavaScript.

Clearly, the need of the hour was to get a cutting-edge technology platform. Technologists found the answer in June 2015, when engineers on the WebKit project, along with Google, Microsoft and Mozilla announced that they were launching WebAssembly. WebAssembly is a new binary format for compiling applications from the web. The idea behind launching WebAssembly was to make it portable bytecode, which can be effective for browsers to download and load.

So what exactly is WebAssembly?

According to, WebAssembly (abbreviated Wasm) is a binary instruction format for a stack-based virtual machine. Wasm is designed to be a portable target for the compilation of high-level languages like C/C++/Rust, enabling deployment on the web for client and server applications. Following are the features of the WebAssembly:

  • Fast Execution
  • Useful in CPU-intensive operation
  • Support for old & new Browsers
  • Secure

WebAssembly is still new, but it is supported in all major browsers such as Chrome, FireFox, Edge, Safari, etc.  Additionally, legacy browsers can be supported with the help of Asm.js. Below is the representation of how WebAssembly works.


                    (Source of the Diagram:

WebAssembly is a relatively new technology. As a result, creating complex applications using this language can be challenging. To understand it better, here are some of the key WebAssembly concepts you need to remember:

  • Module

Represents a WebAssembly binary that has been compiled by the browser into executable machine code.

  • Memory

A resizable array buffer that contains the linear array of bytes read and written by WebAssembly’s low-level memory access instructions.

  • Table

A resizable typed array of references (e.g. to functions) that could not otherwise be stored as raw bytes in Memory (for safety and portability reasons).

  • Instance

A Module paired with all the state it uses at runtime including a Memory, Table, and set of imported values.  An Instance is like an ES2015 module that has been loaded into a particular global with a particular set of imports.

In some ways, WebAssembly gives more power to the web developer. In addition, it changes the dynamics of the web, giving that additional advantage due to its near-native speed.

Some of the advantages include:

Effective and Rapid

WebAssembly performs at native speed by taking advantage of common hardware capabilities accessible on various platforms. The Wasm stack machine is structured to be encoded in a size- and load-time-efficient binary format.


Likewise, Javascript, Wasm describes a memory-safe, sandboxed execution environment. However, WebAseembly can enforce the same-origin and permissions security policies of the browsers once embedded in the web.

Open and Debuggable

WebAssembly is designed to look attractive while having a textual format for debugging, testing, experimenting, optimizing, learning, teaching, and writing programs. The textual format will be used when viewing the source of Wasm modules on the web.

Part of the open web platform

WebAssembly is designed to maintain the versionless, feature-tested, and backward-compatible nature of the web. WebAssembly modules will be able to call into and out of the JavaScript context and access browser functionality through the same Web APIs accessible from JavaScript. WebAssembly also supports non-web embedding.

While everyone is very optimistic about the current state of WebAssembly, there are people who are not well versed with its concepts. Here are some important points, which will help you understand WebAssembly better:

Be very clear that WebAssembly is not Java Applet/Active x, which are plugins. The browser natively supports WebAssembly and it is executed by the same virtual machine, which executes JavaScript. It runs in the same sandbox environment as JavaScript runs. Furthermore, WebAssembly is not a security risk. If you do not consider JavaScript as a security risk, then you should not be worried about WebAssembly as it runs on the same sandbox.

Most importantly, you should know that WebAssembly can not fully manipulate the DOM. It cannot directly access the DOM, but it can call out into JavaScript, and JS can then work on the DOM. Also, lot of people are keen on knowing which languages WebAssembly supports. Currently WebAssembly supports c and c++. Rust is also supporting Webassembly. There are also open source projects, which will add support for garbage collected languages such as C# and Java. Blazor is one such project that enables the development of WebAssembly through c#.


WebAssembly is a promising technology. It is web standard and supported by the most browsers. Nitor’s developers have started taking advantage of this technology where performance is critical. Obviously, there are some limitations for now but as technology evolves, they can be overcome.

Nitor thinks WebAssembly is going to do more of what a modern web browser already does: It is turning out to be a proper, cross-language target for compilers, aiming at supporting all necessary features for making a great all-round platform.