stopping popup windows in a web browser

博客围绕WebBrowser控件展开,提到多数‘不必要’弹窗在Body元素的‘OnLoad’事件发生,可通过判断文档加载是否完成来取消新窗口。代码能将Target='_blank'类型导航重定向到原窗口,允许基于脚本的用户激活链接在新窗口打开。

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edward

(vbCity Leader)


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posts: 1481
since: Apr 8, 2001
from: Shropshire, England

http://www.vbcity.com/forums/topic.asp?tid=22075&highlight=beforenavigate&page=2

Hi,

As most 'unwanted' pop-ups occur during the 'OnLoad' event of the Body element, you can expand on cancelling the NewWindow by determining whether the document being loaded has completed:

Code:

Private Sub WebBrowser1_NewWindow2(ppDisp As Object, Cancel As Boolean)
   If WebBrowser1.Document.ReadyState = "interactive" Then
     ' Probable Script 'OnLoad'
    Cancel = True
    Debug.Print "New Window: Blocked"
   Else
     ' Check if an element has been activated
     If WebBrowser1.Document.activeElement Is Nothing Then
       ' Probable Script
      Cancel = True
      Debug.Print "New Window: Blocked"
     Else
       ' User selection likely
      Debug.Print "New Window: Allowed"
     End If
   End If
End Sub

Private Sub Form_Load()
   ' Ensure the WebBrowser is silent. Cancelled pop-ups often throw a script error:
  WebBrowser1.Silent = True
End Sub



Hope that helps smile

I'm not sure how you can get the NewWindow's target URL without allowing the new window to open.


One of the interesting things about the WebBrowser control is the number of ways you can achieve the same outcome. The expansion on the New Window routine is not elegant but hopefully it gives some indication of the range of possible reasons for a new window.

The code will redirect any Target="_blank" type navigation to the original window, but will allow user-activated links that are script based to open in a new window - this would probably be the point at which to implement a new form and RegisterAsBrowser code. An example is the 'Comment' link in a Microsoft KB article which uses javascript to open the target window.

Code:

Private Sub WebBrowser1_NewWindow2(ppDisp As Object, Cancel As Boolean)
Dim sLink As String
On Error Resume Next
If Not WebBrowser1.Document Is Nothing Then
   If Not WebBrowser1.Document.parentWindow.event Is Nothing Then
     If WebBrowser1.Document.parentWindow.event. Type = "MenuExtUnknown" Then
      
       ' CONTEXT MENU - NAVIGATE
       ' Get the URL of the source Element
      sLink = WebBrowser1.Document.parentWindow.event.srcElement.href
      Debug.Print "Context Menu: " & sLink
       If Len(sLink) > 0 Then
         ' Cancel New Window
        Cancel = True
         ' Force open in current window
        WebBrowser1.Navigate sLink
       End If
     End If
   Else
     If WebBrowser1.Document.activeElement Is Nothing Then
       ' PROBABLE OnLoad SCRIPT - BLOCK
      Debug.Print "Probable Script: Unknown"
      Cancel = True
     Else
    sLink = WebBrowser1.Document.activeElement.href
       If Len(sLink) > 0 Then
         If WebBrowser1.Document.activeElement.protocolLong = "Unknown Protocol" Then
           ' PROBABLE SCRIPTED LINK - ALLOW - *** SET NEW FORM
          Cancel = False
         Else
           ' LINK WITH EXTERNAL TARGET - NAVIGATE
          Debug.Print "External Link Target: " & sLink
          Cancel = True
          WebBrowser1.Navigate sLink
         End If
       Else
         ' UNKNOWN NEW WINDOW
        Debug.Print "Unknown Reason: -"
        Cancel = True
       End If
     End If
   End If
Else
   ' PROBABLE SCRIPT - BLOCK
  Cancel = True
End If
End Sub

The routine checks the protocol of the activeElement's link. Script based navigation will return 'Unknown Protocol'.

Hope that helps smile


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