Tauri Events Targeted Emit

Tauri v2: Targeted Event Emission

Emitter::emit is broadcast — every listener in every window/webview gets it. That is rarely what you want once the app has more than one window. Tauri exposes a small set of addressing primitives; pick deliberately.

The four emit verbs

use tauri::{AppHandle, Emitter, EventTarget};

// 1. Broadcast — everyone, in every window.
app.emit("status-changed", &payload)?;

// 2. One specific window or webview, by label.
app.emit_to("settings", "config-updated", &payload)?;
app.emit_to(EventTarget::webview_window("settings"), "config-updated", &payload)?;

// 3. A set of labels.
app.emit_to(
  EventTarget::labels(["main", "settings"]),
  "theme-changed",
  &theme,
)?;

// 4. Predicate over EventTarget — full control.
app.emit_filter("close-popups", &(), |target| matches!(
  target,
  EventTarget::Webview { label } if label.starts_with("popup-")
))?;

emit_to accepts anything that implements Into<EventTarget>. A bare &str is the common case (= a webview-window label).

EventTarget variants worth knowing

The distinction between Webview and WebviewWindow matters in apps that create extra webviews inside one window (split panes, popovers). For garden-variety multi-window apps, WebviewWindow is what you want.

JS side: who hears what

import { listen, emit, TauriEvent } from '@tauri-apps/api/event';
import { getCurrentWebviewWindow } from '@tauri-apps/api/webviewWindow';

// Listens to events targeted at THIS webview window OR broadcast to all.
const unlisten = await listen<string>('config-updated', (e) => {
  console.log('payload', e.payload, 'from', e.windowLabel);
});

// Explicitly listen on a different target — e.g., the global "main" window.
await listen<Theme>('theme-changed', handler, { target: 'main' });
await listen<Theme>('theme-changed', handler, { target: { kind: 'WebviewWindow', label: 'main' } });

Key rule: a bare listen('foo', …) in window settings receives events that were sent broadcast OR with emit_to("settings", …). It does not receive an event sent with emit_to("main", …) — that one is addressed elsewhere.

To listen for events regardless of target, use the lower-level listen from @tauri-apps/api/event with { target: { kind: 'Any' } }, or call emit_filter/broadcast on the producer side instead.

JS-side emit('foo', payload) is broadcast; use getCurrentWebviewWindow().emit(...) or WebviewWindow.getByLabel('main').emit(...) to scope it.

Decision tree

Does every window need this event?
├── Yes → emit (broadcast)
└── No → How is the target chosen?
        ├── Static set of 1 label    → emit_to("label", …)
        ├── Static set of 2–N labels → emit_to(EventTarget::labels([...]), …)
        ├── Dynamic / pattern match  → emit_filter(|t| …)
        └── Single window + tight coupling to one command's lifetime
                                     → use a Channel<T> instead
                                       (see tauri-events-channels-streaming)

Two common mistakes:

• Broadcasting state that's window-local. A "form is dirty" event broadcast from the settings window wakes every listener app-wide. Scope it.
• Filter where emit_to works. emit_filter runs the closure once per target; for a fixed list of labels, EventTarget::labels is cheaper and clearer.

Templates

• templates/targeted-emit.rs — multi-window app emitting to one window, to a label set, and via a filter (popup pattern).

Related

• tauri-events — parent skill, broadcast events + Rust↔JS basics.
• tauri-events-channels-streaming — when the "target" is really "the one consumer that asked for this stream".
• tauri-windows — creating the labeled windows you're addressing.