Web Assembly: Speed Up Your Website

What Is it?

It is a Programming language. WebAssembly is a new type of code that can be run in modern web browsers (Virtually)— it is a low-level assembly-like language with a compact binary format that runs with near-native performance and provides languages such as C/C++ with a compilation target so that they can run on the web. It is also designed to run alongside JavaScript, allowing both to work together.

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  1. WebAssembly has huge implications for the web platform — it provides a way to run code written in multiple languages on the web at near native speed.
  2. Using the WebAssembly JavaScript APIs, you can load WebAssembly modules into a JavaScript app and share functionality between the two. This allows you to take advantage of WebAssembly’s performance and power and JavaScript’s expressiveness and flexibility in the same apps, even if you don’t know how to write WebAssembly code.
  3. Webpack Sources, one of the core packages of Webpack, and its dependencies source-list-map and source-map are re-written in Rust and compiled to WebAssembly binary to speed up the webpack bundling time.
  4. You can substitute for the old package directly without any modifications in Webpack and plugins.
  5. WebAssembly has an S-expression-based textual representation, an intermediate form designed to be exposed in text editors, browser developer tools, etc.


Efficient and fast

The Wasm stack machine is designed to be encoded in a size- and load-time-efficient binary format. WebAssembly aims to execute at native speed by taking advantage of common hardware capabilities available on a wide range of platforms.


WebAssembly describes a memory-safe, sandboxed execution environment that may even be implemented inside existing JavaScript virtual machines. When embedded in the web, WebAssembly will enforce the same-origin and permissions security policies of the browser.

Open and debuggable

WebAssembly is designed to be pretty-printed in a textual format for debugging, testing, experimenting, optimizing, learning, teaching, and writing programs by hand. 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 embeddings.


The cost of downloading, parsing, and compiling very large JavaScript applications can be prohibitive.  Mobile and other resource-constrained platforms can further amplify these performance bottlenecks.

How Does this Work?

The web platform can be thought of as having two parts:

  • A virtual machine (VM) that runs the Web app’s code, e.g. the JavaScript code that powers your apps.
  • A set of Web APIs that the Web app can call to control web browser/device functionality.

WebAssembly is a different language from JavaScript, but it is not intended as a replacement. Instead, it is designed to complement and work alongside JavaScript, allowing web developers to take advantage of both languages’ strong points:

JavaScript is a high-level language, flexible and expressive enough to write web applications.  It has many advantages — it is dynamically typed, requires no compile step, and has a huge ecosystem that provides powerful frameworks, libraries, and other tools.

With the advent of WebAssembly appearing in browsers, the virtual machine will now load and run two types of code — JavaScript AND WebAssembly.
The different code types can call each other as required — the WebAssembly JavaScript API wraps exported WebAssembly code with JavaScript functions that can be called normally, and WebAssembly code can import and synchronously call normal JavaScript functions.

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