在Internet Explorer中使用VB.Net捕获Javascript警报

使用下面的代码，您可以自动关闭JavaScript警报窗口，获取消息文本或发送点击消息到警报窗口上的按钮。

WindowStateChanged事件不触发JavaScript警报显示(在我的环境中)。如果触发，可以使用下面的代码。

<DllImport("user32.dll", SetLastError:=True)> _
Private Shared Function GetForegroundWindow() As IntPtr
End Function
Private Sub aaxWebBrowser1_WindowStateChanged(sender As Object, e As AxSHDocVw.DWebBrowserEvents2_WindowStateChangedEvent)
    HandleJavascriptAlertwindows(GetForegroundWindow(), False)
End Sub 

或者您可以使用ForeGroundWindowWatcher类来捕获JavaScript警报窗口。如果AxWebbrowser在一个表单上，你应该改变Me.ParentForm。处理到Me。处理

Private ForeGroundWindowWatcher_ As ForeGroundWindowWatcher
Private Sub StartForeGroundWatcher()
    ForeGroundWindowWatcher_ = New ForeGroundWindowWatcher
    AddHandler ForeGroundWindowWatcher_.ForegroundWindowHasChanged, AddressOf ForeGroundWindowWatcher_ForegroundWindowHasChanged
    ForeGroundWindowWatcher_.Startt()
End Sub
Private Sub StopForeGroundWatcher()
    If ForeGroundWindowWatcher_ IsNot Nothing Then
        RemoveHandler ForeGroundWindowWatcher_.ForegroundWindowHasChanged, AddressOf ForeGroundWindowWatcher_ForegroundWindowHasChanged
        ForeGroundWindowWatcher_.Stopp()
    End If
End Sub
Private Sub btnStartForeGroundWatcher_Click(sender As System.Object, e As System.EventArgs) Handles btnStartForeGroundWatcher.Click
    'Should be called inside form_load event
    StartForeGroundWatcher()
End Sub
Private Sub btnStopForeGroundWatcher_Click(sender As System.Object, e As System.EventArgs) Handles btnStopForeGroundWatcher.Click
    'Should be called inside form_Closing event
    StopForeGroundWatcher()
End Sub
Private Sub ForeGroundWindowWatcher_ForegroundWindowHasChanged(sender As Object, ForeGroundWindowHandle As IntPtr)
    HandleJavascriptAlertwindows(ForeGroundWindowHandle, False)
End Sub
Private LastForeGroundWindowHandle As IntPtr = IntPtr.Zero
Private Sub HandleJavascriptAlertwindows(ForeGroundWindowHandle As IntPtr, preventFromShowing As Boolean)
    Try
        'source http://www.vbforums.com/showthread.php?761005-WebBrowser-Control-how-to-handle-Javascript-generated-alert-window-%28onbeforeunload%29
        'Dim hwnd = FindWindow("#32770", "Windows Internet Explorer")' this finds windows from its title.
        Dim hwnd = ForeGroundWindowHandle 'GetForegroundWindow() 'get the foreground window
        If hwnd = IntPtr.Zero Then Return
        'Get forgroundwindow cvlassname. Classname of JavaScript alert windows is "#32770"
        Dim ForeGroundWindowClassName As String = ForeGroundWindowHelper.GetClassNameFromHandle(hwnd)
        Dim MeHandle As IntPtr = Me.ParentForm.Handle 'use Me.Handle if ME is a form. 
        'Debug.WriteLine(WindowClassName)
        Dim AlertMessage As String = ""
        Debug.WriteLine("ForeGroundWindowHandle: " + ForeGroundWindowHandle.ToString)
        Debug.WriteLine("MeHandle: " + MeHandle.ToString)
        Debug.WriteLine("ForeGroundWindowClassName: " + ForeGroundWindowClassName)
        If String.CompareOrdinal("#32770", ForeGroundWindowClassName) = 0 Then
            If LastForeGroundWindowHandle <> IntPtr.Zero AndAlso LastForeGroundWindowHandle <> MeHandle Then
                'Alert might be shown another webbrowser.
                Return
            End If
            For Each ch As ForeGroundWindowHelper.WindowChildInfo In ForeGroundWindowHelper.GetChildWindows(hwnd)
                Debug.WriteLine("Text: " + ch.Text)
                Debug.WriteLine("ClassName: " + ch.ClassName)
                If ch.ClassName.ToLower = "static" Then
                    AlertMessage = ch.Text
                End If
                If preventFromShowing Then
                    'close alert by sending ESC
                    SendKeys.Send("{ESC}")
                    'or
                    ''send click event to specific button
                    'If ch.ClassName = "Button" AndAlso ch.Text = "OK" Then
                    '    ForeGroundWindowHelper.SendClickEvet2Button(ch.hWnd)
                    '    Exit For
                    'End If
                End If
            Next
        End If
        Debug.WriteLine("AlertMessage: " + AlertMessage)
        LastForeGroundWindowHandle = ForeGroundWindowHandle
    Catch ex As Exception
        Debug.WriteLine(ex.Message)
    End Try
End Sub

Imports System.Runtime.InteropServices
Imports System.Text
Public Class ForeGroundWindowWatcher
    'original source https://stackoverflow.com/questions/4372055/detect-active-window-changed-using-c-sharp-without-polling
    'Stephen Lee Parker
    Public Event ForeGroundWindowHasChanged(sender As Object, ForeGroundWindowHandle As IntPtr)
    Private dele As WinEventDelegate = Nothing
    Private Const WINEVENT_OUTOFCONTEXT As UInteger = 0
    Private Const EVENT_SYSTEM_FOREGROUND As UInteger = 3
    Private m_hhook As IntPtr = IntPtr.Zero
    Public Sub Startt()
        If m_hhook <> IntPtr.Zero Then
            Return
        End If
        dele = New WinEventDelegate(AddressOf WinEventProc)
        m_hhook = SetWinEventHook(EVENT_SYSTEM_FOREGROUND, EVENT_SYSTEM_FOREGROUND, IntPtr.Zero, dele, 0, 0, WINEVENT_OUTOFCONTEXT)
        If m_hhook = IntPtr.Zero Then
            Throw New Exception("SetWinEventHook failed")
        End If
    End Sub
    Public Sub Stopp()
        If m_hhook <> IntPtr.Zero Then
            UnhookWinEvent(m_hhook)
        End If
    End Sub
    Private Delegate Sub WinEventDelegate(hWinEventHook As IntPtr,
                                          eventType As UInteger,
                                          hwnd As IntPtr,
                                          idObject As Integer,
                                          idChild As Integer,
                                          dwEventThread As UInteger,
                                          dwmsEventTime As UInteger)
    <DllImport("user32.dll")> _
    Private Shared Function SetWinEventHook(eventMin As UInteger,
                                            eventMax As UInteger,
                                            hmodWinEventProc As IntPtr,
                                            lpfnWinEventProc As WinEventDelegate,
                                            idProcess As UInteger,
                                            idThread As UInteger,
                                            dwFlags As UInteger) As IntPtr
    End Function
    <DllImport("user32.dll")> _
    Private Shared Function UnhookWinEvent(hWinEventHook As IntPtr) As Boolean
    End Function
    Public Sub WinEventProc(hWinEventHook As IntPtr,
                            eventType As UInteger,
                            hwnd As IntPtr,
                            idObject As Integer,
                            idChild As Integer,
                            dwEventThread As UInteger,
                            dwmsEventTime As UInteger)
        RaiseEvent ForeGroundWindowHasChanged(Me, hwnd)
    End Sub
End Class

WebBrowser控件如何处理Javascript生成的警报窗口

Imports System.Runtime.InteropServices
Imports System.Text
Public Class ForeGroundWindowHelper
    'source http://www.vbforums.com/showthread.php?761005-WebBrowser-Control-how-to-handle-Javascript-generated-alert-window-%28onbeforeunload%29
    'by AgustinTRC
    Public Class WindowChildInfo
        Public hWnd As IntPtr
        Public ClassName As String
        Public Text As String
        Public Sub New(hwnd As IntPtr, clsname As String, text As String)
            Me.hWnd = hwnd
            Me.ClassName = clsname
            Me.Text = text
        End Sub
    End Class
    Private Const BM_CLICK As Integer = &HF5
    Private Const WM_ACTIVATE As Integer = &H6
    Private Const WA_ACTIVE As Integer = 1
    <DllImport("user32.dll", CharSet:=CharSet.Auto, EntryPoint:="FindWindow")> _
    Private Shared Function FindWindow(ByVal lpClassName As String, ByVal lpWindowName As String) As IntPtr
    End Function
    <DllImport("user32.dll", EntryPoint:="SendMessage")> _
    Private Shared Function SendMessage(hwnd As IntPtr, wMsg As Integer, wParam As Integer, lParam As Integer) As IntPtr
    End Function
    ' private...
    <DllImport("user32.dll", CharSet:=CharSet.Auto)> _
    Private Shared Sub GetClassName(ByVal hWnd As System.IntPtr, ByVal lpClassName As StringBuilder, ByVal nMaxCount As Integer)
    End Sub
    <DllImport("user32.dll", SetLastError:=True, CharSet:=CharSet.Auto)> _
    Private Shared Function GetWindowText(ByVal hwnd As IntPtr, ByVal lpString As StringBuilder, ByVal cch As Integer) As Integer
    End Function
    <DllImport("user32.dll", SetLastError:=True, CharSet:=CharSet.Auto)> _
    Private Shared Function GetWindowTextLength(ByVal hwnd As IntPtr) As Integer
    End Function

    Private Delegate Function EnumCallBackDelegate(ByVal hwnd As IntPtr, ByVal lParam As IntPtr) As Integer
    Private Declare Function EnumChildWindows Lib "user32" (ByVal hWndParent As IntPtr, ByVal lpEnumFunc As EnumCallBackDelegate, ByVal lParam As IntPtr) As IntPtr

    Private Shared children As List(Of WindowChildInfo)
    Public Shared Function GetChildWindows(ByVal hwnd As IntPtr) As List(Of WindowChildInfo)
        children = New List(Of WindowChildInfo)
        EnumChildWindows(hwnd, AddressOf EnumProc, Nothing)
        Return children
    End Function
    Private Shared Function EnumProc(ByVal hwnd As IntPtr, ByVal lParam As IntPtr) As Int32
        If hwnd <> IntPtr.Zero Then
            children.Add(New WindowChildInfo(hwnd, GetClassNameFromHandle(hwnd), GetText(hwnd)))
        End If
        Return 1
    End Function
    Public Shared Function GetClassNameFromHandle(ByVal hWnd As IntPtr) As String
        Dim sbClassName As New StringBuilder("", 256)
        Call GetClassName(hWnd, sbClassName, 256)
        Return sbClassName.ToString
    End Function
    Private Shared Function GetText(ByVal hWnd As IntPtr) As String
        Dim length As Integer = GetWindowTextLength(hWnd)
        If length = 0 Then Return ""
        Dim sb As New StringBuilder("", length + 1)
        GetWindowText(hWnd, sb, sb.Capacity)
        Return sb.ToString()
    End Function
    Public Shared Sub SendClickEvet2Button(ByVal hWnd As IntPtr)
        ' activate the button
        SendMessage(hWnd, WM_ACTIVATE, WA_ACTIVE, 0)
        ' send button a click message
        SendMessage(hWnd, BM_CLICK, 0, 0)
    End Sub
End Class

注入javascript。

(function(w){
  w.____oldAlert = w.alert;
  w.alert = function(msg){
    console.log("alert(", msg, ");");
    var result = w.____oldAlert(msg);
    console.log("returned ", result);
    return result;
  };
})(window);

类似的代码可以应用于confirm和prompt，因此您不必依赖许多hack，可以读取返回值。如果有一天IE决定像Chrome那样改变显示对话框的方式，你的代码仍然可以正常工作

我想如果你看看这个问题的顶部答案，你就会找到你要找的东西。这里的代码是用C编写的，但是响应者指出所有必要的信息都在那里。