WP7 web browser script extensions

WebBrowserScriptExtensions.cs

using System;
using Microsoft.Phone.Controls;

public static class WebBrowserScriptExtensions
{
    public static object ExecuteCode(this WebBrowser browser, string code)
    {
        return browser.InvokeScript("eval", "(function(){\r\n" + code + "\r\n})();");
    }

    public static object SetVariable(this WebBrowser browser, string name, string code, bool overrideScript = false)
    {
        if (overrideScript)
        {
            return browser.InvokeScript("eval",
                "this." + name + " = " + code + ";");
        }
        else
        {
            return browser.InvokeScript("eval",
                "if(!this." + name + ") {\r\n" + "this." + name + " = " + code + "; \r\n}");
        }
    }

    public static object NotifyOnScriptError(this WebBrowser browser, string code = "", bool overrideScript = false)
    {
        if (string.IsNullOrEmpty(code))
        {
            code = "window.external.notify(JSON.stringify({message: message, file: file, line: line}));";
        }

        return browser.SetVariable("onerror", "function(message, file, line) {\r\n " + code + "\r\n}", overrideScript);
    }

    public static string GetHtml(this WebBrowser browser)
    {
        return (string)browser.ExecuteCode("return document.documentElement.outerHTML");
    }

    public class JavascriptExecption : Exception
    {
        public JavascriptExecption(string message, string file, long line)
            : base(message)
        {
            File = file;
            Line = line;
        }

        public JavascriptExecption(string message, string file, string line)
            : this(message, file, long.Parse(line))
        {
        }

        public string File { get; private set; }
        public long Line { get; private set; }
    }
}

WebBrowserScriptExtensionsSample.cs

var x = webBrowser1.SetVariable("msg", @"function() { return 'hi'; }");
var y = webBrowser1.InvokeScript("msg"); // y === 'hi'

webBrowser1.NotifyOnScriptError();
webBrowser1.ExecuteCode("throw new Error('heello')");
private void webBrowser1_ScriptNotify(object sender, NotifyEventArgs e)
{
    Debug.WriteLine(e.Value);
}

var z = webBrowser1.ExecuteCode("window.external.notify('hi');");