Web

ashlar’s headless core (commands, documents, files, jobs, logging) builds for wasm32-unknown-unknown, and CI checks it. Running the windowed app in a browser is experimental: it works, and examples/web-hello builds in the gate, but not every feature is there.

The example

use ashlar::prelude::*;

#[derive(Clone, Default, serde::Serialize, serde::Deserialize)]
struct Doc {
    clicks: u32,
}

fn main() -> Result<(), ashlar::app::Error> {
    App::<Doc>::new("web-hello", env!("CARGO_PKG_VERSION"))
        .title("Hello, web")
        .canvas_id("web-hello")
        .view(|ui, cx: &mut Cx<'_, Doc>| {
            let t = cx.tokens();
            ui.heading("Hello from ashlar on the web");
            ui.add_space(t.space.md);
            if ui.button("Click").clicked() {
                cx.edit("Click", |d| d.clicks = d.clicks.saturating_add(1));
            }
            ui.label(format!("Clicked {} times (undo with Ctrl/Cmd+Z)", cx.doc().clicks));
        })
        .run()
}

The same code opens a window on the desktop. On the web the app runs in the <canvas> named by App::canvas_id (default: the app’s name, then ashlar). If it cannot start (no such canvas, no WebGL), a visible error appears next to the canvas as well as in the console.

Dependencies

Turn off the default features: headless has no meaning in a browser. Keep accesskit for screen readers.

[dependencies]
ashlar = { package = "ashlar-rs", version = "0.2", default-features = false, features = ["accesskit"] }
serde = { version = "1", features = ["derive"] }

Building and serving

The example uses trunk, which runs wasm-bindgen and serves the page:

rustup target add wasm32-unknown-unknown
trunk serve examples/web-hello/index.html

The page needs a canvas with the right id and a trunk link to the binary:

<link data-trunk rel="rust" data-bin="ashlar-example-web-hello">
<canvas id="web-hello"></canvas>

What differs on the web

• Jobs run inline, with no threads. Use spawn_stepped for long work so it advances a few steps per frame.
• The disk-backed settings and files compile but report errors; use the in-memory backends or a browser-storage backend (ashlar::fs::ConfigStore).
• File dialogs can only open files.
• The tray, global shortcuts, notifications, the clipboard, single instance, the control port and record and replay are not available.