VB.Net Webview2 How can I get html source code?

Question

I sucessfully display a web site on WebView2 in my VB.net (Visual Studio 2017) project but can not get html souce code. Please advise me how to get html code.

My code:

Private Sub testbtn_Click(sender As Object, e As EventArgs) Handles testbtn.Click
        WebView2.CoreWebView2.Navigate("https://www.microsoft.com/")
End Sub

Private Sub WebView2_NavigationCompleted(sender As Object, e As CoreWebView2NavigationCompletedEventArgs) Handles WebView2.NavigationCompleted
        Dim html As String = ?????
End Sub

Thank you indeed for your advise in advance.

I've never used a `WebView2` control and there seems to be little information around about this but I suspect that it starts [here](https://learn.microsoft.com/en-us/microsoft-edge/webview2/reference/dotnet/0-9-538/microsoft-web-webview2-core-corewebview2#getdevtoolsprotocoleventreceiver). I think the reason that it's not well documented is that it's part of Chromium. — jmcilhinney, Jun 17 '20 at 15:06
Does this answer your question? [How I get page source from WebView?](https://stackoverflow.com/questions/9966760/how-i-get-page-source-from-webview) — J. Scott Elblein, Jun 17 '20 at 19:18
Also, https://stackoverflow.com/questions/29654149/get-source-code-from-webview-vb-for-metro — J. Scott Elblein, Jun 17 '20 at 19:18
Thank you indeed. I have read through the document but still can not find the answer. I also tried the link "https://stackoverflow.com/questions/29654149/get-source-code-from-webview-vb-for-metro" but unfortunately "Await myWebView.InvokeScriptAsync" is marked error and does not work. — Tom, Jun 17 '20 at 22:56

score 30 · Accepted Answer · answered Jun 19 '20 at 00:05

30

I've only just started messing with the WebView2 earlier today as well, and was just looking for this same thing. I did manage to scrape together this solution:

Dim html As String
html = Await WebView2.ExecuteScriptAsync("document.documentElement.outerHTML;")

' The Html comes back with unicode character codes, other escaped characters, and
' wrapped in double quotes, so I'm using this code to clean it up for what I'm doing.
html = Regex.Unescape(html)
html = html.Remove(0, 1)
html = html.Remove(html.Length - 1, 1)

Converted my code from C# to VB on the fly, so hopefully didn't miss any syntax errors.

answered Jun 19 '20 at 00:05

Xaviorq8

316
3
2

1

Fantastic. Thank you indeed. I can acomplish getting html source code from WebView2 as in followoing code. I really appreciate for it. Private Sub testbtn_Click() Handles testbtn.Click wv.CoreWebView2.Navigate(""https://www.microsoft.com/"") End Sub Private Async Sub wv_NavigationCompleted() Handles wv.NavigationCompleted Dim html As String = String.Empty html = Await wv.ExecuteScriptAsync("document.documentElement.outerHTML;") html = Regex.Unescape(html) html = html.Remove(0, 1) html = html.Remove(html.Length - 1, 1) End Sub – Tom Jun 19 '20 at 05:20
But, what about simply invoking the "View Page Source" command in WebBiew2? Can we do that? I know we can display it via a hot key so why not "on demand"? This command would display the source in a popup window. – Andrew Truckle Apr 18 '22 at 18:54
Your answer was exactly what I needed. I was using WebBrowser.DocumentStream to load HtmlAgilityPack.HtmlDocument. Now I am converting to WebView2 and I could not get a valid document into HtmlAgilityPack. Your answer solved the problem. Perhaps I will post my code tomorrow in case it would help someone. – Ken Smith Sep 28 '22 at 05:52

score 3 · Answer 2 · answered Dec 01 '20 at 11:37

3

Adding to @Xaviorq8 answer, you can use Span to get rid of generating new strings with Remove:

html = Regex.Unescape(html)
html = html.AsSpan()[1..^1].ToString();

answered Dec 01 '20 at 11:37

JohnyL

6,894
3
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score 1 · Answer 3 · answered Sep 30 '22 at 19:02

I must credit @Xaviorq8; his answer was needed to solve my problem. I was successfully using .NET WebBrowser and Html Agility Pack but I wanted to replace WebBrowser with .NET WebView2.

Snippet (working code with WebBrowser):

using HAP = HtmlAgilityPack;
HAP.HtmlDocument hapHtmlDocument = null;
hapHtmlDocument = new HAP.HtmlDocument();
hapHtmlDocument.Load(webBrowser1.DocumentStream);
HtmlNodeCollection nodes = hapHtmlDocument.DocumentNode.SelectNodes("//*[@id=\"apptAndReportsTbl\"]");

Snippet (failing code with WebView2):

using HAP = HtmlAgilityPack;
HAP.HtmlDocument hapHtmlDocument = null;
string html = await webView21.ExecuteScriptAsync("document.documentElement.outerHTML");
hapHtmlDocument = new HAP.HtmlDocument();
hapHtmlDocument.LoadHtml(html);
HtmlNodeCollection nodes = hapHtmlDocument.DocumentNode.SelectNodes("//*[@id=\"apptAndReportsTbl\"]");

Success withWebView2 and Html Agility Pack

using HAP = HtmlAgilityPack;
HAP.HtmlDocument hapHtmlDocument = null;
string html = await webView21.ExecuteScriptAsync("document.documentElement.outerHTML");
// thanks to @Xaviorq8 answer (next 3 lines)
html = Regex.Unescape(html);
html = html.Remove(0, 1);
html = html.Remove(html.Length - 1, 1);
hapHtmlDocument = new HAP.HtmlDocument();
hapHtmlDocument.LoadHtml(html);
HtmlNodeCollection nodes = hapHtmlDocument.DocumentNode.SelectNodes("//*[@id=\"apptAndReportsTbl\"]");

score 0 · Answer 4 · answered Oct 08 '22 at 17:51

The accepted answer is on the right track. However, it's missing on important thing:

The returned string is NOT HTMLEncoded, it's JSON!

So to do it right, you need to deserialize the JSON, which is just as simple:

Dim html As String
html = Await WebView2.ExecuteScriptAsync("document.documentElement.outerHTML;")
html = Await JsonSerializer.DeserializeAsync(Of String)(html);

VB.Net Webview2 How can I get html source code?

4 Answers4

Snippet (working code with WebBrowser):

Snippet (failing code with WebView2):

Success withWebView2 and Html Agility Pack

Linked