如何在VB.net中使用"ExecuteScriptAsync“方法获取返回值？

Question

我在VB.net应用程序中使用CefSharp作为浏览器，并希望从浏览器中检索返回值。

我只能在C#中找到解决方案，但我不能在VisualBasic中使其工作。

在这段代码中，我得到了以下错误：“error: Result不是Task的成员”

Dim script = "var returnValue = function(){ var value; value=10-2; return value; }"
        Dim task As Threading.Tasks.Task = browser.EvaluateScriptAsync(script)
        Dim taskResult As String

        task.ContinueWith(Sub(t)
                              If t.IsFaulted = False Then
                                  Dim response = t.Result 'Error: Result is not a member of Task' 
                                  If response.Success And response.Result IsNot Nothing Then
                                      taskResult = response.Result
                                  End If
                              End If
                          End Sub)

        MsgBox(taskResult)

这是我在CefSharp文档中找到的C#版本，但我无法将其转换为VB.net：

browser.EvaluateScriptAsync(script).ContinueWith(x =>
        {
            var response = x.Result;

            if (response.Success && response.Result != null)
            {
                var onePlusOne = (int)response.Result;
                //Do something here (To interact with the UI you must call BeginInvoke)
            }      
        });

Answer 1

我更改了你的Javascript，让它返回值。根据注释中的建议，我更改了task的声明以更正您提到的错误。

Dim script = "(function(){ var value; value=10-2; return value; })();"
Dim task As Task(Of JavascriptResponse) = browser.EvaluateScriptAsync(script)
Dim taskResult As String

task.ContinueWith(
    Sub(t)
        If t.IsFaulted = False Then
            Dim response = t.Result 'Error: Result is not a member of Task' 
            If response.Success And response.Result IsNot Nothing Then
                taskResult = response.Result
            End If
        End If
    End Sub)

MsgBox(task.Result.Result)

Answer 2

    Dim html As String = ""
    Using t As Task(Of String) = WebView21.ExecuteScriptAsync("document.documentElement.outerHTML;")
        Do Until t.IsCompleted
            Application.DoEvents()
        Loop
        html = t.Result
    End Using
    html = Regex.Unescape(html)
    html = html.Remove(0, 1)
    html = html.Remove(html.Length - 1, 1)
    html = html.Replace("<!--!-->", "")