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)
Section 1: Introduction to WebAssembly
Section 2: WebAssembly Tools
Section 3: Rust and WebAssembly

Converting Rust into WebAssembly via rustc

Rust uses the LLVM compiler we'll create now to generate machine-native code. rustc uses LLVM's capability to convert the native code into a WebAssembly module. We installed Rust in the previous section; let's start converting Rust into a WebAssembly module using rustc.

We will start with Hello World:

  1. Let's create a file called
    $ touch
  2. Spin up your favorite editor and start writing the Rust code:
    fn main() {    
    println!("Hello World!");

We have defined a main function. Similar to C, main is a special function that marks the entry point to a program after it has been compiled as an executable.

fn is the function keyword in Rust. main() is the function name.

println! is the macro. Macros in Rust allow us to abstract code at a syntactic level. A macro invocation is shorthand for an "expanded" syntactic form. This expansion...