How to wait until WebBrowser is completely loaded in VB.NET?

Shubham picture Shubham · Jul 18, 2010 · Viewed 115.6k times · Source

I am using the WebBrowser control in my VB.NET application to load a few URLs ( ~10-15) and save their HTML source in a text file. However, my code doesn't write the source of the current page rather the initial one because the it is triggered even before the page is loaded.

How can I wait until the page is completely loaded before calling any event?

I tried the following code but it doesn't work.

Do Until WebBrowser1.ReadyState = WebBrowserReadyState.Complete
   Application.DoEvents()
Loop

Answer

bgmCoder picture bgmCoder · Feb 9, 2012

Salvete! I needed, simply, a function I could call to make the code wait for the page to load before it continued. After scouring the web for answers, and fiddling around for several hours, I came up with this to solve for myself, the exact dilemma you present. I know I am late in the game with an answer, but I wish to post this for anyone else who comes along.

usage: just call WaitForPageLoad() just after a call to navigation:

whatbrowser.Navigate("http://www.google.com")
WaitForPageLoad()

another example we don't combine the navigate feature with the page load, because sometimes you need to wait for a load without also navigating, for example, you might need to wait for a page to load that was started with an invokemember event:

whatbrowser.Document.GetElementById("UserName").InnerText = whatusername
whatbrowser.Document.GetElementById("Password").InnerText = whatpassword
whatbrowser.Document.GetElementById("LoginButton").InvokeMember("click")
WaitForPageLoad()

Here is the code: You need both subs plus the accessible variable, pageready. First, make sure to fix the variable called whatbrowser to be your webbrowser control

Now, somewhere in your module or class, place this:

Private Property pageready As Boolean = False

#Region "Page Loading Functions"
    Private Sub WaitForPageLoad()
        AddHandler whatbrowser.DocumentCompleted, New WebBrowserDocumentCompletedEventHandler(AddressOf PageWaiter)
        While Not pageready
            Application.DoEvents()
        End While
        pageready = False
    End Sub

    Private Sub PageWaiter(ByVal sender As Object, ByVal e As WebBrowserDocumentCompletedEventArgs)
        If whatbrowser.ReadyState = WebBrowserReadyState.Complete Then
            pageready = True
            RemoveHandler whatbrowser.DocumentCompleted, New WebBrowserDocumentCompletedEventHandler(AddressOf PageWaiter)
        End If
    End Sub

#End Region