Book Image

Practical WebAssembly

By : Sendil Kumar Nellaiyapen
Book Image

Practical WebAssembly

By: Sendil Kumar Nellaiyapen

Overview of this book

Rust is an open source language tuned toward safety, concurrency, and performance. WebAssembly brings all the capabilities of the native world into the JavaScript world. Together, Rust and WebAssembly provide a way to create robust and performant web applications. They help make your web applications blazingly fast and have small binaries. Developers working with JavaScript will be able to put their knowledge to work with this practical guide to developing faster and maintainable code. Complete with step-by-step explanations of essential concepts, examples, and self-assessment questions, you’ll begin by exploring WebAssembly, using the various tools provided by the ecosystem, and understanding how to use WebAssembly and JavaScript together to build a high-performing application. You’ll then learn binary code to work with a variety of tools that help you to convert native code into WebAssembly. The book will introduce you to the world of Rust and the ecosystem that makes it easy to build/ship WebAssembly-based applications. By the end of this WebAssembly Rust book, you’ll be able to create and ship your own WebAssembly applications using Rust and JavaScript, understand how to debug, and use the right tools to optimize and deliver high-performing applications.
Table of Contents (15 chapters)
1
Section 1: Introduction to WebAssembly
5
Section 2: WebAssembly Tools
9
Section 3: Rust and WebAssembly

Understanding how WebAssembly works

Let's first explore how JavaScript and WebAssembly are executed inside the JavaScript engine.

Understanding JavaScript execution inside the JavaScript engine

The JavaScript engine first fetches the complete JavaScript file (note that the engine has to wait until the entire file is downloaded/loaded).

Note

The bigger the JavaScript file, the longer it takes to load. It doesn't matter how fast your JavaScript engine is or how efficient your code is. If your JavaScript file is huge (that is, greater than 170 KB), then your application is going to be slow at loading time.

Figure 3.1 – JavaScript execution inside the JavaScript engine

Once loaded, the JavaScript is parsed into abstract syntax trees (ASTs). This phase is called parse. Since JavaScript is both an interpreted and compiled language, the JavaScript engine kickstarts the execution after parsing. The interpreter executes the code faster...