事件系統

Wails 提供用於發布／訂閱通訊的統一事件系統。您可以在任何位置發出及監聽事件——從 Go 到 JavaScript、從 JavaScript 到 Go，以及從視窗到視窗——透過具型別的事件和生命週期掛鉤實現解耦架構。

快速入門

Go（發出）：

app.Event.Emit("user-logged-in", map[string]interface{}{
    "userId": 123,
    "name": "Alice",
})

JavaScript（監聽）：

javascript

import { Events } from '@wailsio/runtime'

Events.On("user-logged-in", (event) => {
    console.log(`User ${event.data.name} logged in`)
})

就這麼簡單！跨語言發布／訂閱。

事件類型

自訂事件

應用程式專屬的事件：

// Emit from Go
app.Event.Emit("order-created", order)
app.Event.Emit("payment-processed", payment)
app.Event.Emit("notification", message)

javascript

// Listen in JavaScript
Events.On("order-created", handleOrder)
Events.On("payment-processed", handlePayment)
Events.On("notification", showNotification)

系統事件

內建的作業系統與應用程式事件：

import "github.com/wailsapp/wails/v3/pkg/events"

// Theme changes
app.Event.OnApplicationEvent(events.Common.ThemeChanged, func(e *application.ApplicationEvent) {
    if e.Context().IsDarkMode() {
        app.Logger.Info("Dark mode enabled")
    }
})

// Application lifecycle
app.Event.OnApplicationEvent(events.Common.ApplicationStarted, func(e *application.ApplicationEvent) {
    app.Logger.Info("Application started")
})

視窗事件

視窗專屬事件：

window.OnWindowEvent(events.Common.WindowFocus, func(e *application.WindowEvent) {
    app.Logger.Info("Window focused")
})

window.OnWindowEvent(events.Common.WindowClosing, func(e *application.WindowEvent) {
    app.Logger.Info("Window closing")
})

發出事件

從 Go 發出

基本發出方式：

app.Event.Emit("event-name", data)

使用不同的資料類型：

// String
app.Event.Emit("message", "Hello")

// Number
app.Event.Emit("count", 42)

// Struct
app.Event.Emit("user", User{ID: 1, Name: "Alice"})

// Map
app.Event.Emit("config", map[string]interface{}{
    "theme": "dark",
    "fontSize": 14,
})

// Array
app.Event.Emit("items", []string{"a", "b", "c"})

發送至特定視窗：

window.EmitEvent("window-specific-event", data)

從 JavaScript 發出

javascript

import { Events } from '@wailsio/runtime'

// Emit to Go
Events.Emit("button-clicked", { buttonId: "submit" })

// Emit to all windows
Events.Emit("broadcast-message", "Hello everyone")

監聽事件

在 Go 中

應用程式事件：

app.Event.On("custom-event", func(e *application.CustomEvent) {
    data := e.Data
    // Handle event
})

使用型別斷言：

app.Event.On("user-updated", func(e *application.CustomEvent) {
    user := e.Data.(User)
    app.Logger.Info("User updated", "name", user.Name)
})

多個處理常式：

// All handlers will be called
app.Event.On("order-created", logOrder)
app.Event.On("order-created", sendEmail)
app.Event.On("order-created", updateInventory)

在 JavaScript 中

基本監聽器：

javascript

import { Events } from '@wailsio/runtime'

Events.On("event-name", (event) => {
    console.log("Event received:", event.data)
})

包含清理作業：

javascript

const unsubscribe = Events.On("event-name", handleEvent)

// Later, stop listening
unsubscribe()

多個處理常式：

javascript

Events.On("data-updated", updateUI)
Events.On("data-updated", saveToCache)
Events.On("data-updated", logChange)

單次處理常式：

javascript

Events.Once("data-updated", updateVariable)

系統事件

應用程式事件

常見事件（跨平台）：

import "github.com/wailsapp/wails/v3/pkg/events"

// Application started
app.Event.OnApplicationEvent(events.Common.ApplicationStarted, func(e *application.ApplicationEvent) {
    app.Logger.Info("App started")
})

// Theme changed
app.Event.OnApplicationEvent(events.Common.ThemeChanged, func(e *application.ApplicationEvent) {
    isDark := e.Context().IsDarkMode()
    app.Event.Emit("theme-changed", isDark)
})

// System about to suspend
app.Event.OnApplicationEvent(events.Common.SystemWillSleep, func(e *application.ApplicationEvent) {
    flushPendingWrites()
})

// System resumed from suspend
app.Event.OnApplicationEvent(events.Common.SystemDidWake, func(e *application.ApplicationEvent) {
    reconnectSockets()
    refreshState()
})

// File opened
app.Event.OnApplicationEvent(events.Common.ApplicationOpenedWithFile, func(e *application.ApplicationEvent) {
    // Single-file: e.Context().Filename() returns ""; for multi-file launches
    // (Finder "Open With..." → multiple selection) use OpenedFiles().
    filePath := e.Context().Filename()
    openFile(filePath)
})

平台專屬事件：

// Application became active
app.Event.OnApplicationEvent(events.Mac.ApplicationDidBecomeActive, func(e *application.ApplicationEvent) {
    app.Logger.Info("App became active")
})

// Application will terminate
app.Event.OnApplicationEvent(events.Mac.ApplicationWillTerminate, func(e *application.ApplicationEvent) {
    cleanup()
})

// System about to sleep / resumed
app.Event.OnApplicationEvent(events.Mac.ApplicationWillSleep, func(e *application.ApplicationEvent) {
    flushPendingWrites()
})
app.Event.OnApplicationEvent(events.Mac.ApplicationDidWake, func(e *application.ApplicationEvent) {
    refreshState()
})

// Displays sleeping/waking — distinct from system sleep (e.g. lid lowered)
app.Event.OnApplicationEvent(events.Mac.ApplicationScreensDidSleep, func(e *application.ApplicationEvent) {
    pauseRendering()
})
app.Event.OnApplicationEvent(events.Mac.ApplicationScreensDidWake, func(e *application.ApplicationEvent) {
    resumeRendering()
})

// Power status changed
app.Event.OnApplicationEvent(events.Windows.APMPowerStatusChange, func(e *application.ApplicationEvent) {
    app.Logger.Info("Power status changed")
})

// System suspending
app.Event.OnApplicationEvent(events.Windows.APMSuspend, func(e *application.ApplicationEvent) {
    saveState()
})

// System resumed. APMResumeAutomatic always fires on resume;
// APMResumeSuspend fires after it when the wake was triggered by
// user input. Prefer Common.SystemDidWake if you don't need to
// distinguish.
app.Event.OnApplicationEvent(events.Windows.APMResumeAutomatic, func(e *application.ApplicationEvent) {
    refreshState()
})

// Application startup
app.Event.OnApplicationEvent(events.Linux.ApplicationStartup, func(e *application.ApplicationEvent) {
    app.Logger.Info("App starting")
})

// Theme changed
app.Event.OnApplicationEvent(events.Linux.SystemThemeChanged, func(e *application.ApplicationEvent) {
    updateTheme()
})

// System sleep/wake — sourced from systemd-logind's PrepareForSleep
// signal on the system bus. Requires logind/elogind exposing
// org.freedesktop.login1, so it may be unavailable on distros/setups
// without it (Alpine, Void, some Devuan setups).
app.Event.OnApplicationEvent(events.Linux.SystemWillSleep, func(e *application.ApplicationEvent) {
    flushPendingWrites()
})
app.Event.OnApplicationEvent(events.Linux.SystemDidWake, func(e *application.ApplicationEvent) {
    refreshState()
})

視窗事件

常見視窗事件：

// Window focus
window.OnWindowEvent(events.Common.WindowFocus, func(e *application.WindowEvent) {
    app.Logger.Info("Window focused")
})

// Window blur
window.OnWindowEvent(events.Common.WindowLostFocus, func(e *application.WindowEvent) {
    app.Logger.Info("Window blurred")
})

// Window closing
window.OnWindowEvent(events.Common.WindowClosing, func(e *application.WindowEvent) {
    if hasUnsavedChanges() {
        e.Cancel()  // Prevent close
    }
})

// Window closed
window.OnWindowEvent(events.Common.WindowClosing, func(e *application.WindowEvent) {
    cleanup()
})

事件掛鉤

掛鉤會在標準監聽器之前執行，並且可以取消事件：

// Hook - runs first, can cancel
window.RegisterHook(events.Common.WindowClosing, func(e *application.WindowEvent) {
    if hasUnsavedChanges() {
        result := showConfirmdialog("Unsaved changes. Close anyway?")
        if result != "yes" {
            e.Cancel()  // Prevent window close
        }
    }
})

// Standard listener - runs after hooks
window.OnWindowEvent(events.Common.WindowClosing, func(e *application.WindowEvent) {
    app.Logger.Info("Window closing")
})

主要差異：

功能	掛鉤	標準監聽器
執行順序	最先執行，依註冊順序	在掛鉤之後執行，順序不保證
阻塞	同步，會阻塞下一個掛鉤	非同步，不阻塞
可否取消	可以	不可以（已傳播）
使用情境	控制流程、驗證	記錄、附帶作用

事件模式

發布／訂閱模式

// Publisher (service)
type OrderService struct {
    app *application.App
}

func (o *OrderService) CreateOrder(items []Item) (*Order, error) {
    order := &Order{Items: items}
    
    if err := o.saveOrder(order); err != nil {
        return nil, err
    }
    
    // Publish event
    o.app.Event.Emit("order-created", order)
    
    return order, nil
}

// Subscribers
app.Event.On("order-created", func(e *application.CustomEvent) {
    order := e.Data.(*Order)
    sendConfirmationEmail(order)
})

app.Event.On("order-created", func(e *application.CustomEvent) {
    order := e.Data.(*Order)
    updateInventory(order)
})

app.Event.On("order-created", func(e *application.CustomEvent) {
    order := e.Data.(*Order)
    logOrder(order)
})

請求／回應模式

// Frontend requests data
Emit("get-user-data", { userId: 123 })

// Backend responds
app.Event.On("get-user-data", func(e *application.CustomEvent) {
    data := e.Data.(map[string]interface{})
    userId := int(data["userId"].(float64))
    
    user := getUserFromDB(userId)
    
    // Send response
    app.Event.Emit("user-data-response", user)
})

javascript

// Frontend receives response
Events.On("user-data-response", (event) => {
    const user = event.data
    displayUser(user)
})

注意：對於請求／回應，繫結是更好的選擇。請使用事件來傳送通知。

廣播模式

// Broadcast to all windows
app.Event.Emit("global-notification", "System update available")

// Each window handles it
Events.On("global-notification", (event) => {
    const message = event.data
    showNotification(message)
})

事件彙總

type EventAggregator struct {
    events []Event
    mu     sync.Mutex
}

func (ea *EventAggregator) Add(event Event) {
    ea.mu.Lock()
    defer ea.mu.Unlock()
    
    ea.events = append(ea.events, event)
    
    // Emit batch every 100 events
    if len(ea.events) >= 100 {
        app.Event.Emit("event-batch", ea.events)
        ea.events = nil
    }
}

完整範例

Go：

package main

import (
    "github.com/wailsapp/wails/v3/pkg/application"
    "github.com/wailsapp/wails/v3/pkg/events"
)

type NotificationService struct {
    app *application.App
}

func (n *NotificationService) Notify(message string) {
    // Emit to all windows
    n.app.Event.Emit("notification", map[string]interface{}{
        "message":   message,
        "timestamp": time.Now(),
    })
}

func main() {
    app := application.New(application.Options{
        Name: "Event Demo",
    })
    
    notifService := &NotificationService{app: app}
    
    // System events
    app.Event.OnApplicationEvent(events.Common.ThemeChanged, func(e *application.ApplicationEvent) {
        isDark := e.Context().IsDarkMode()
        app.Event.Emit("theme-changed", isDark)
    })
    
    // Custom events from frontend
    app.Event.On("user-action", func(e *application.CustomEvent) {
        data := e.Data.(map[string]interface{})
        action := data["action"].(string)
        
        app.Logger.Info("User action", "action", action)
        
        // Respond
        notifService.Notify("Action completed: " + action)
    })
    
    // Window events
    window := app.Window.New()
    
    window.OnWindowEvent(events.Common.WindowFocus, func(e *application.WindowEvent) {
        app.Event.Emit("window-focused", window.Name())
    })
    
    window.RegisterHook(events.Common.WindowClosing, func(e *application.WindowEvent) {
        // Confirm before close
        app.Event.Emit("confirm-close", nil)
        e.Cancel()  // Wait for confirmation
    })
    
    app.Run()
}

JavaScript：

javascript

import { Events } from '@wailsio/runtime'

// Listen for notifications
Events.On("notification", (event) => {
    showNotification(event.data.message)
})

// Listen for theme changes
Events.On("theme-changed", (event) => {
    const isDark = event.data
    document.body.classList.toggle('dark', isDark)
})

// Listen for window focus
Events.On("window-focused", (event) => {
    const windowName = event.data
    console.log(`Window ${windowName} focused`)
})

// Handle close confirmation
Events.On("confirm-close", (event) => {
    if (confirm("Close window?")) {
        Events.Emit("close-confirmed", true)
    }
})

// Emit user actions
document.getElementById('button').addEventListener('click', () => {
    Events.Emit("user-action", { action: "button-clicked" })
})

最佳實務

✅ 建議做法

使用事件傳送通知——單向通訊
使用繫結處理請求——雙向通訊
保持事件名稱一致——使用 kebab-case
記錄事件資料的規格——其中包含哪些欄位？
完成後取消訂閱——防止記憶體流失
使用掛鉤進行驗證——控制事件流程

❌ 請勿

請勿使用事件進行 RPC——請改用繫結
不要過於頻繁地發出事件——必要時批次處理
不要在處理常式中阻塞——讓處理常式保持快速
不要忘記取消訂閱——否則會造成記憶體洩漏
不要使用事件傳輸大量資料——請使用繫結
不要形成事件迴圈——A 發出 B，B 又發出 A

後續步驟

事件指南

瞭解事件模式和型別安全的事件產生方式。

深入瞭解 →

事件 API

探索完整的應用程式與視窗事件 API。

深入瞭解 →

繫結

使用繫結進行要求／回應。

深入瞭解 →

視窗事件

處理視窗生命週期事件。

深入瞭解 →

有問題嗎？請在Discord中提問，或查看事件範例。

無障礙功能

編輯此文件

事件系統

事件系統

快速入門

事件類型

自訂事件

系統事件

視窗事件

發出事件

從 Go 發出

從 JavaScript 發出

監聽事件

在 Go 中

在 JavaScript 中

系統事件

應用程式事件

視窗事件

事件掛鉤

事件模式

發布／訂閱模式

請求／回應模式

廣播模式

事件彙總

完整範例

最佳實務

✅ 建議做法

❌ 請勿

後續步驟