WPF WebBrowser JS Errors capture

Definition of the problem: Catch all the JS errors occurred in WebBrowser used in WPF application.

Luckily DOM's window has so called "external" object and WebBrowser componenet has a "ObjectForScripting" property which is "equal" to "window.external".

There are some restrictions with permissions, f.e. you cannot set your window or application as a ObjectForScripting. Otherwise you receive Exception "The object type is not visible to COM. You need to set ComVisibleAttribute attribute to True."
So I propose to use another class to do that.

Here is the source:
1st Part of code is run only once, in the window/app constructor f.e.

ObjectForScriptingHelper ScriptHelper = new ObjectForScriptingHelper(this);
wb_browser.ObjectForScripting = ScriptHelper;

2nd Part is run on Browser's "Navigated" event

private void wb_browser_Navigated(object sender, System.Windows.Navigation.NavigationEventArgs e) {
 string DisableScriptError = @"function externalError(errorMsg, document, lineNumber) {
  window.external.onError(errorMsg, document, lineNumber);
  return true;
 }
 window.onerror = externalError;";
 HTMLDocument doc2 = wb_browser.Document as HTMLDocument;
 IHTMLScriptElement scriptErrorSuppressed = (IHTMLScriptElement)doc2.createElement("SCRIPT");
 scriptErrorSuppressed.type = "text/javascript";
 scriptErrorSuppressed.text = DisableScriptError;
 IHTMLElementCollection nodes = doc2.getElementsByTagName("head");
 foreach (IHTMLElement elem in nodes)
 {

  HTMLHeadElement head = (HTMLHeadElement)elem;
  head.appendChild((IHTMLDOMNode)scriptErrorSuppressed);
 }
}

3rd Part of script is that special class:

[PermissionSet(SecurityAction.Demand, Name = "FullTrust")]
[ComVisible(true)]
public class ObjectForScriptingHelper
{
 TestingWindow m_Window;

 public ObjectForScriptingHelper(TestingWindow w)
 {
  m_Window = w;
 }

 public void onError(Object arg1, Object arg2, Object arg3)
 {
  m_Window.onError(arg1, arg2, arg3);
 }
}

And 4th Part of code is point where you can write your code:

public void onError(Object arg1, Object arg2, Object arg3) {
 //Put your handle here
}

GL & HF


SE keywords:
How to capture script error message in a WPF WebBrowser