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 WAST into JSON

The wast2json tool reads the WAST format and parses it, checks for errors, and then converts WAST into the JSON file. It generates a JSON and WASM file associated with the WAST file. Then, it links the WASM inside the JSON:

$ /path/to/build/directory/of/wabt/wast2json add.wat -o add.
$ cat add.json
{"source_filename": "add.wat",
"commands": [
{"type": "module", "line": 1, "filename": "add.0.wasm"}]}

To check the various options supported by wast2json, run the following command:

$ /path/to/build/directory/of/wabt/wast2json --help
usage: wast2json [options] filename
  read a file in the wasm spec test format, check it for 
  errors, and
  convert it to a JSON file and associated wasm binary files.
  # parse spec-test.wast, and write files to spec-test.json. 
  Modules are
  # written...