如何从浏览器c#返回javascript函数值

how to return javascript function value from webbrowser c#

本文关键字：javascript 函数返回浏览器更新时间：2023-09-26

Awesomium浏览器提供JavaScript execute with result方法返回如下值:

private const String JS_FAVICON = "(function(){links = document.getElementsByTagName('link'); wHref=window.location.protocol + '//' + window.location.hostname + '/favicon.ico'; for(i=0; i<links.length; i++){s=links[i].rel; if(s.indexOf('icon') != -1){ wHref = links[i].href }; }; return wHref; })();";
string val = webControl.ExecuteJavascriptWithResult(JS_FAVICON);

然而，我需要执行这与c#内置浏览器如何做到这一点，我认为有方法"webBrowser1.Document。不知道如何使用它…

编辑……这就是Awesomium浏览器返回值的方式:

private void Awesomium_Windows_Forms_WebControl_DocumentReady(object  sender, UrlEventArgs e)
    {
        // DOM is ready. We can start looking for a favicon.
        //UpdateFavicon();
    }

 private void UpdateFavicon()
    {
        // Execute some simple javascript that will search for a favicon.
        string val = webControl.ExecuteJavascriptWithResult(JS_FAVICON);
        // Check for any errors.
        if (webControl.GetLastError() != Error.None)
            return;
        // Check if we got a valid response.
        if (String.IsNullOrEmpty(val) || !Uri.IsWellFormedUriString(val, UriKind.Absolute))
            return;
        // We do not need to perform the download of the favicon synchronously.
        // May be a full icon set (thus big).
        Task.Factory.StartNew<Icon>(GetFavicon, val).ContinueWith(t =>
        {
            // If the download completed successfully, set the new favicon.
            // This post-completion procedure is executed synchronously.
            if (t.Exception != null)
                return;
            if (t.Result != null)
                this.Icon = t.Result;
            if (this.DockPanel != null)
                this.DockPanel.Refresh();
        },
        TaskScheduler.FromCurrentSynchronizationContext());
    }
    private static Icon GetFavicon(Object href)
    {
        using (WebClient client = new WebClient())
        {
            Byte[] data = client.DownloadData(href.ToString());
            if ((data == null) || (data.Length <= 0))
                return null;
            using (MemoryStream ms = new MemoryStream(data))
            {
                try
                {
                    return new Icon(ms, 16, 16);
                }
                catch (ArgumentException)
                {
                    // May not be an icon file.
                    using (Bitmap b = new Bitmap(ms))
                        return Icon.FromHandle(b.GetHicon());
                }
            }
        }
    }

，这是我在WinForm浏览器中做的:

 private void webBrowser1_DocumentCompleted(object sender,   WebBrowserDocumentCompletedEventArgs e)
 {
        UpdateFavicon();
 }
 private void UpdateFavicon()
 {
   var obj = webBrowser1.Document.InvokeScript("_X_");
   string val = webBrowser1.DocumentText = "<script> function _X_(){return " + JS_FAVICON + ";} </script>"; 
 }

正如@JohnSmith所说的，这不是不可能的

用一个简单的技巧你可以从javascript

得到返回值

string JS_FAVICON = "(function(){links = document.getElementsByTagName('link'); wHref=window.location.protocol + '//' + window.location.hostname + '/favicon.ico'; for(i=0; i<links.length; i++){s=links[i].rel; if(s.indexOf('icon') != -1){ wHref = links[i].href }; }; return wHref; })();";
webBrowser1.DocumentCompleted += (s, e) =>
{
    var obj = webBrowser1.Document.InvokeScript("_X_");
    //obj will be about:///favicon.ico
    //write your code that handles the return value here
};
string val = webBrowser1.DocumentText = "<script> function _X_(){return " + JS_FAVICON + ";} </script>";

但是由于我们可以在DocumentCompleted处理程序中获得该值，因此不能直接调用方法返回该值。如果你能用这种方法继续你的工作，那就没问题了。如果没有，那么它需要更多的技巧来完成它。让我知道……

这里是完整的工作代码，只需调用TestJavascript在您的表单的某个地方。

async void TestJavascript()
{
    string JS_FAVICON = "(function(){links = document.getElementsByTagName('link'); wHref=window.location.protocol + '//' + window.location.hostname + '/favicon.ico'; for(i=0; i<links.length; i++){s=links[i].rel; if(s.indexOf('icon') != -1){ wHref = links[i].href }; }; return wHref; })();";
    var retval = await Execute(webBrowser1, JS_FAVICON);
    MessageBox.Show(retval.ToString());
}
Task<object> Execute(WebBrowser wb,  string anonJsFunc)
{
    var tcs = new TaskCompletionSource<object>();
    WebBrowserDocumentCompletedEventHandler documentCompleted = null;
    documentCompleted = (s, e) =>
    {
        var obj = wb.Document.InvokeScript("_X_");
        tcs.TrySetResult(obj);
        wb.DocumentCompleted -= documentCompleted; //detach
    };
    wb.DocumentCompleted += documentCompleted; //attach
    string val = wb.DocumentText = "<script> function _X_(){return " +
                                    anonJsFunc +
                                    ";} </script>";
    return tcs.Task;
}