rust-wasm

from pluginagentmarketplace/custom-plugin-rust

Rust programming language roadmap plugin for Claude

1 stars0 forksUpdated Jan 5, 2026
npx skills add https://github.com/pluginagentmarketplace/custom-plugin-rust --skill rust-wasm

SKILL.md

Rust WebAssembly Skill

Master WebAssembly with Rust: wasm-pack, wasm-bindgen, JavaScript interop, and browser integration.

Quick Start

Setup

# Install wasm-pack
cargo install wasm-pack

# Add target
rustup target add wasm32-unknown-unknown

# Create project
cargo new --lib my-wasm
cd my-wasm

Project Configuration

# Cargo.toml
[package]
name = "my-wasm"
version = "0.1.0"
edition = "2021"

[lib]
crate-type = ["cdylib", "rlib"]

[dependencies]
wasm-bindgen = "0.2"
js-sys = "0.3"
web-sys = { version = "0.3", features = ["console", "Window", "Document"] }

[dev-dependencies]
wasm-bindgen-test = "0.3"

[profile.release]
lto = true
opt-level = "z"

Basic WASM Module

// src/lib.rs
use wasm_bindgen::prelude::*;

// Import JavaScript function
#[wasm_bindgen]
extern "C" {
    #[wasm_bindgen(js_namespace = console)]
    fn log(s: &str);
}

// Export Rust function to JavaScript
#[wasm_bindgen]
pub fn greet(name: &str) -> String {
    format!("Hello, {}!", name)
}

#[wasm_bindgen]
pub fn add(a: i32, b: i32) -> i32 {
    a + b
}

// Initialize (called on load)
#[wasm_bindgen(start)]
fn main() {
    log("WASM module loaded!");
}

Build

# Build for bundlers (webpack, etc.)
wasm-pack build

# Build for web (no bundler)
wasm-pack build --target web

# Build for Node.js
wasm-pack build --target nodejs

# Build optimized
wasm-pack build --release

JavaScript Integration

Using in Browser (No Bundler)

<!DOCTYPE html>
<html>
<head>
    <script type="module">
        import init, { greet, add } from './pkg/my_wasm.js';

        async function run() {
            await init();

            const message = greet("World");
            console.log(message);  // "Hello, World!"

            const sum = add(2, 3);
            console.log(sum);  // 5
        }

        run();
    </script>
</head>
<body></body>
</html>

Using with Webpack

// index.js
import * as wasm from "my-wasm";

console.log(wasm.greet("Webpack"));

Using with npm

# Build and pack
wasm-pack build
cd pkg
npm link

# In JavaScript project
npm link my-wasm

DOM Manipulation

use wasm_bindgen::prelude::*;
use web_sys::{Document, Element, HtmlElement, Window};

#[wasm_bindgen]
pub fn manipulate_dom() -> Result<(), JsValue> {
    // Get window and document
    let window = web_sys::window().unwrap();
    let document = window.document().unwrap();

    // Create element
    let div = document.create_element("div")?;
    div.set_id("my-div");
    div.set_inner_html("<h1>Hello from Rust!</h1>");

    // Add to body
    document.body().unwrap().append_child(&div)?;

    // Query selector
    let element = document.query_selector("#my-div")?.unwrap();

    // Add event listener
    let closure = Closure::wrap(Box::new(move |_event: web_sys::MouseEvent| {
        web_sys::console::log_1(&"Clicked!".into());
    }) as Box<dyn FnMut(_)>);

    element.add_event_listener_with_callback(
        "click",
        closure.as_ref().unchecked_ref()
    )?;

    closure.forget();  // Keep closure alive

    Ok(())
}

Async/Await in WASM

use wasm_bindgen::prelude::*;
use wasm_bindgen_futures::JsFuture;
use web_sys::{Request, RequestInit, Response};

#[wasm_bindgen]
pub async fn fetch_data(url: &str) -> Result<JsValue, JsValue> {
    let opts = RequestInit::new();
    opts.set_method("GET");

    let request = Request::new_with_str_and_init(url, &opts)?;

    let window = web_sys::window().unwrap();
    let resp_value = JsFuture::from(window.fetch_with_request(&request)).await?;

    let resp: Response = resp_value.dyn_into()?;
    let json = JsFuture::from(resp.json()?).await?;

    Ok(json)
}

Structs and Complex Types

use wasm_bindgen::prelude::*;
use serde::{Deserialize, Serialize};

#[wasm_bindgen]
pub struct Point {
    x: f64,
    y: f64,
}

#[wasm_bindgen]
impl Point {
    #[wasm_bindgen(constructor)]
    pub fn new(x: f64, y: f64) -> Point {
        Point { x, y }
    }

    #[wasm_bindgen(getter)]
    pub fn x(&self) -> f64 {
        self.x
    }

    #[wasm_bindgen(getter)]
    pub fn y(&self) -> f64 {
        self.y
    }

    pub fn distance(&self, other: &Point) -> f64 {
        ((self.x - other.x).powi(2) + (self.y - other.y).powi(2)).sqrt()
    }
}

// For complex types, use serde
#[derive(Serialize, Deserialize)]
pub struct Config {
    name: String,
    values: Vec<i32>,
}

#[wasm_bindgen]
pub fn parse_config(json: &str) -> Result<JsValue, JsValue> {
    let config: Config = serde_json::from_str(json)
        .map_err(|e| JsValue::from_str(&e.to_string()))?;

    Ok(serde_wasm_bindgen::to_value(&config)?)
}

Memory Management

use wasm_bindgen::prelude::*;

// Typed arrays for efficient data transfer
#[wasm_bindgen]
pub fn process_array(data: &[u8]) -> Vec<u8> {
    data.iter().map(|x| x.wrapping_add(1)).collect()
}

// Zero-copy view into WASM memory
#[wasm_bindgen]
pub fn get_mem

...
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