tauri-syntax-events

Quick Reference

Rust Event Traits (Tauri 2.x)

Trait	Implemented By	Purpose
Emitter	App, AppHandle, Webview, WebviewWindow, Window	Send events
Listener	App, AppHandle, Webview, WebviewWindow, Window	Receive events

Emitter Methods

Method	Scope	Description
emit(event, payload)	Global	Broadcast to ALL listeners
emit_str(event, payload)	Global	Broadcast with pre-serialized JSON string
emit_to(target, event, payload)	Targeted	Send to a specific window/webview label
emit_filter(event, payload, filter_fn)	Filtered	Send to targets matching a predicate

Listener Methods

Method	Fires	Returns
listen(event, handler)	Every time	EventId
once(event, handler)	Once, then auto-removes	EventId
listen_any(event, handler)	Every time, any source	EventId
once_any(event, handler)	Once, any source	EventId
unlisten(id)	N/A	()

Frontend Event API (TypeScript)

Function	Import	Description
listen<T>(event, handler, options?)	@tauri-apps/api/event	Listen for events, returns Promise<UnlistenFn>
once<T>(event, handler, options?)	@tauri-apps/api/event	Listen once, returns Promise<UnlistenFn>
emit(event, payload?)	@tauri-apps/api/event	Broadcast event globally
emitTo(target, event, payload?)	@tauri-apps/api/event	Send event to specific target

TauriEvent Built-in Events

Member	Value
WINDOW_RESIZED	"tauri://resize"
WINDOW_MOVED	"tauri://move"
WINDOW_CLOSE_REQUESTED	"tauri://close-requested"
WINDOW_DESTROYED	"tauri://destroyed"
WINDOW_FOCUS	"tauri://focus"
WINDOW_BLUR	"tauri://blur"
WINDOW_SCALE_FACTOR_CHANGED	"tauri://scale-change"
WINDOW_THEME_CHANGED	"tauri://theme-changed"
WINDOW_CREATED	"tauri://window-created"
WEBVIEW_CREATED	"tauri://webview-created"
DRAG_ENTER	"tauri://drag-enter"
DRAG_OVER	"tauri://drag-over"
DRAG_DROP	"tauri://drag-drop"
DRAG_LEAVE	"tauri://drag-leave"

---

Critical Warnings

NEVER forget Clone on event payload structs — emit() requires Serialize + Clone. Omitting Clone causes a compile error that does not clearly indicate the source.

NEVER use special characters in event names — only alphanumeric, -, /, :, and _ are allowed. Other characters cause a runtime panic.

NEVER forget to call the unlisten function in frontend components — this causes memory leaks. In React, ALWAYS clean up in the useEffect return function.

NEVER forget to await the listen() call in TypeScript — listen() returns Promise<UnlistenFn>, not UnlistenFn directly.

ALWAYS import the Emitter trait (use tauri::Emitter;) before calling emit() in Rust — the method is not available without the trait import.

ALWAYS import the Listener trait (use tauri::Listener;) before calling listen() in Rust.

---

Essential Patterns

Pattern 1: Rust to Frontend (Emitter)

// Tauri 2.x — Broadcast from Rust to all frontend listeners
use tauri::Emitter;

#[derive(Clone, serde::Serialize)]
struct ProgressUpdate {
    task_id: String,
    percent: f64,
    message: String,
}

// In a command or setup hook:
app_handle.emit("progress", ProgressUpdate {
    task_id: "download-1".into(),
    percent: 45.5,
    message: "Downloading file...".into(),
})?;

Pattern 2: Frontend Listening

// Tauri 2.x — Listen in TypeScript
import { listen } from '@tauri-apps/api/event';

interface ProgressUpdate {
  taskId: string;
  percent: number;
  message: string;
}

const unlisten = await listen<ProgressUpdate>('progress', (event) => {
  console.log(`${event.payload.taskId}: ${event.payload.percent}%`);
});

// When done:
unlisten();

Pattern 3: Frontend to Rust (Emit + Listen)

// Tauri 2.x — Frontend emits
import { emit } from '@tauri-apps/api/event';

await emit('user-action', { action: 'save', documentId: 42 });

// Tauri 2.x — Rust listens (typically in setup hook)
use tauri::Listener;

app.listen("user-action", |event| {
    println!("User action: {:?}", event.payload());
});

Pattern 4: Targeted Emission

// Tauri 2.x — Emit to specific window
use tauri::Emitter;

app_handle.emit_to("main", "notification", "Update available")?;

// Emit with filter
app_handle.emit_filter("sync", payload, |target| {
    matches!(target, tauri::EventTarget::WebviewWindow { label } if label != "settings")
})?;

// Tauri 2.x — Frontend targeted emit
import { emitTo } from '@tauri-apps/api/event';

await emitTo('settings', 'config-changed', { key: 'theme', value: 'dark' });

Pattern 5: React Cleanup Pattern

// Tauri 2.x — Correct cleanup in React useEffect
import { listen } from '@tauri-apps/api/event';

useEffect(() => {
  let unlisten: (() => void) | undefined;

  listen<string>('update', (event) => {
    setState(event.payload);
  }).then((fn) => { unlisten = fn; });

  return () => {
    if (unlisten) unlisten();
  };
}, []);

Pattern 6: Once (Single-Fire Listener)

// Tauri 2.x — Rust: listen once, auto-removes
use tauri::Listener;

app.once("initialization-complete", |event| {
    println!("App initialized: {:?}", event.payload());
});

// Tauri 2.x — TypeScript: listen once
import { once } from '@tauri-apps/api/event';

await once<string>('app-ready', (event) => {
  console.log('App initialized:', event.payload);
});

---

TypeScript Event Types

type EventName = string; // alphanumeric, hyphens, slashes, colons, underscores
type EventCallback<T> = (event: Event<T>) => void;
type UnlistenFn = () => void;

interface Event<T> {
  event: EventName;
  id: number;
  payload: T;
}

interface Options {
  target?: string | EventTarget;
}

type EventTarget =
  | { kind: 'Any' }
  | { kind: 'AnyLabel'; label: string }
  | { kind: 'Window'; label: string }
  | { kind: 'Webview'; label: string }
  | { kind: 'WebviewWindow'; label: string };

---

Permissions Required

Events require core:event:default in the capability file:

{
  "$schema": "../gen/schemas/desktop-schema.json",
  "identifier": "default",
  "windows": ["main"],
  "permissions": [
    "core:event:default"
  ]
}

---

Reference Links

• references/methods.md — Complete Emitter and Listener trait signatures
• references/examples.md — Working code examples for common event scenarios
• references/anti-patterns.md — What NOT to do, with WHY explanations

Official Sources

• https://v2.tauri.app/develop/calling-rust/#event-system
• https://docs.rs/tauri/2/tauri/trait.Emitter.html
• https://docs.rs/tauri/2/tauri/trait.Listener.html
• https://v2.tauri.app/reference/javascript/api/namespaceevent/