Create a Rust-based Web Assembly application

readme.md

• Install rustup and the latest version of Rust

  arungupt@Aruns-MBP-52212 ~ % curl --proto '=https' --tlsv1.2 https://sh.rustup.rs -sSf | sh
  info: downloading installer
  
  Welcome to Rust!
  
  This will download and install the official compiler for the Rust
  programming language, and its package manager, Cargo.
  
  Rustup metadata and toolchains will be installed into the Rustup
  home directory, located at:
  
    /Users/arungupt/.rustup
  
  This can be modified with the RUSTUP_HOME environment variable.
  
  The Cargo home directory is located at:
  
    /Users/arungupt/.cargo
  
  This can be modified with the CARGO_HOME environment variable.
  
  The cargo, rustc, rustup and other commands will be added to
  Cargo's bin directory, located at:
  
    /Users/arungupt/.cargo/bin
  
  This path will then be added to your PATH environment variable by
  modifying the profile files located at:
  
    /Users/arungupt/.profile
    /Users/arungupt/.zshenv
  
  You can uninstall at any time with rustup self uninstall and
  these changes will be reverted.
  
  Current installation options:
  
  
     default host triple: aarch64-apple-darwin
       default toolchain: stable (default)
                 profile: default
    modify PATH variable: yes
  
  1) Proceed with installation (default)
  2) Customize installation
  3) Cancel installation
  >
  
  info: profile set to 'default'
  info: default host triple is aarch64-apple-darwin
  info: syncing channel updates for 'stable-aarch64-apple-darwin'
  732.1 KiB / 732.1 KiB (100 %) 543.4 KiB/s in  1s ETA:  0s
  info: latest update on 2023-06-01, rust version 1.70.0 (90c541806 2023-05-31)
  info: downloading component 'cargo'
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  info: downloading component 'rustfmt'
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  info: installing component 'rustfmt'
  info: default toolchain set to 'stable-aarch64-apple-darwin'
  
    stable-aarch64-apple-darwin installed - rustc 1.70.0 (90c541806 2023-05-31)
  
  
  Rust is installed now. Great!
  
  To get started you may need to restart your current shell.
  This would reload your PATH environment variable to include
  Cargo's bin directory ($HOME/.cargo/bin).
  
  To configure your current shell, run:
  source "$HOME/.cargo/env"
  

• Create Rust program

  mkdir projects 
  cd projects 
  mkdir hello_world 
  cd hello_world 
  vi main.rs
  

  Add the following code:

  fn main() {
      println!("Hello, world!");
  }
  

• Compile and run the code:

  arungupt@Aruns-MBP-52212 hello_world % rustc main.rs 
  arungupt@Aruns-MBP-52212 hello_world % ./main  
  
  Hello, world! 
  

• Install wasm-pack

  arungupt@Aruns-MBP-52212 hello_world % cargo install wasm-pack
  
      Updating crates.io index
    Downloaded wasm-pack v0.11.1
    Downloaded 1 crate (426.1 KB) in 22.78s
    Installing wasm-pack v0.11.1
      Updating crates.io index
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    Downloaded 191 crates (23.6 MB) in 15m 52s (largest was `openssl-src` at 5.1 MB)
     Compiling libc v0.2.146
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     Compiling wasm-pack v0.11.1
      Finished release [optimized] target(s) in 17m 15s
    Installing /Users/arungupt/.cargo/bin/wasm-pack
     Installed package `wasm-pack v0.11.1` (executable `wasm-pack`)
  

• Build the wasm package

  arungupt@Aruns-MBP-52212 hello-wasm % wasm-pack build --target web
  [INFO]: 🎯  Checking for the Wasm target...
  info: downloading component 'rust-std' for 'wasm32-unknown-unknown'
  info: installing component 'rust-std' for 'wasm32-unknown-unknown'
  [INFO]: 🌀  Compiling to Wasm...
     Compiling proc-macro2 v1.0.60
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     Compiling unicode-ident v1.0.9
     Compiling wasm-bindgen-shared v0.2.86
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     Compiling cfg-if v1.0.0
     Compiling syn v2.0.18
     Compiling wasm-bindgen-backend v0.2.86
     Compiling wasm-bindgen-macro-support v0.2.86
     Compiling wasm-bindgen-macro v0.2.86
     Compiling hello-wasm v0.1.0 (/Users/arungupt/projects/hello-wasm)
      Finished release [optimized] target(s) in 6.85s
  [WARN]: ⚠️   origin crate has no README
  [INFO]: License key is set in Cargo.toml but no LICENSE file(s) were found; Please add the LICENSE file(s) to your project directory
  [INFO]: ⬇️  Installing wasm-bindgen...
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    Downloaded 44 crates (2.4 MB) in 1.77s
     Compiling libc v0.2.146
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     Compiling wasm-bindgen-cli v0.2.86
      Finished release [optimized] target(s) in 29.20s
  warning: the following packages contain code that will be rejected by a future version of Rust: buf_redux v0.8.4, multipart v0.18.0
  note: to see what the problems were, use the option `--future-incompat-report`, or run `cargo report future-incompatibilities --id 1`
    Installing /Users/arungupt/Library/Caches/.wasm-pack/.wasm-bindgen-cargo-install-0.2.86/bin/wasm-bindgen
    Installing /Users/arungupt/Library/Caches/.wasm-pack/.wasm-bindgen-cargo-install-0.2.86/bin/wasm-bindgen-test-runner
    Installing /Users/arungupt/Library/Caches/.wasm-pack/.wasm-bindgen-cargo-install-0.2.86/bin/wasm2es6js
     Installed package `wasm-bindgen-cli v0.2.86` (executables `wasm-bindgen`, `wasm-bindgen-test-runner`, `wasm2es6js`)
  warning: be sure to add `/Users/arungupt/Library/Caches/.wasm-pack/.wasm-bindgen-cargo-install-0.2.86/bin` to your PATH to be able to run the installed binaries
  [INFO]: Optimizing wasm binaries with `wasm-opt`...
  [INFO]: ✨   Done in 44.34s
  [INFO]: 📦   Your wasm pkg is ready to publish at /Users/arungupt/projects/hello-wasm/pkg.
  

• Update Rust code in hello-wasm/src/lib.rs to this:

  use wasm_bindgen::prelude::*;
  
  #[wasm_bindgen]
  extern {
      pub fn alert(s: &str);
  }
  
  #[wasm_bindgen]
  pub fn greet(name: &str) {
      alert(&format!("Hello, {}!", name));
  }
  

• Update hello-wasm/Cargo.toml to this:

  [package]
  name = "hello-wasm"
  version = "0.1.0"
  authors = ["Your Name <you@example.com>"]
  description = "A sample project with wasm-pack"
  license = "MIT/Apache-2.0"
  repository = "https://github.com/yourgithubusername/hello-wasm"
  edition = "2018"
  
  [lib]
  crate-type = ["cdylib"]
  
  [dependencies]
  wasm-bindgen = "0.2"
  

• Build the package

  arungupt@Aruns-MBP-52212 hello-wasm % wasm-pack build --target web
  

• Create hello-wasm/index.html

  <!DOCTYPE html>
  <html lang="en-US">
    <head>
      <meta charset="utf-8" />
      <title>hello-wasm example</title>
    </head>
    <body>
      <script type="module">
        import init, { greet } from "./pkg/hello_wasm.js";
        init().then(() => {
          greet("WebAssembly");
        });
      </script>
    </body>
  </html>
  

• Start a local web server:

  python3 -m http.server
  

• Access the webssembly-enabled web application at http://localhost:8000