Question

我有一个访问过的网页，使用以下内容声明一个名为date的变量：

var date=new Date("03 Oct 2013 16:04:19");

然后该日期显示在页面顶部。有没有办法让我修改那个日期变量？（而不仅仅是可见的HTML源代码）

我一直在尝试使用InvokeScript，但我发现很难掌握，如果有人知道并且可以发布一些与此直接相关的例子，我将非常感激。三江源。

Answer 1

您可以使用JavaScript的eval注入任何JavaScript代码，它适用于任何IE版本。您需要确保该网页至少有一个<script>代码，但这很简单：

Public Class Form1

    Private Sub Form1_Load(sender As Object, e As EventArgs) Handles MyBase.Load
        Call WebBrowser1.Navigate("http://example.com")
    End Sub

    Private Sub WebBrowser1_DocumentCompleted(sender As Object, e As WebBrowserDocumentCompletedEventArgs) Handles WebBrowser1.DocumentCompleted
        '
        ' use WebBrowser1.Document.InvokeScript to inject script
        '
        ' make sure the page has at least one script element, so eval works
        WebBrowser1.Document.Body.AppendChild(WebBrowser1.Document.CreateElement("script"))
        WebBrowser1.Document.InvokeScript("eval", New [Object]() {"(function() { window.newDate=new Date('03 Oct 2013 16:04:19'); })()"})
        Dim result As String = WebBrowser1.Document.InvokeScript("eval", New [Object]() {"(function() { return window.newDate.toString(); })()"})
        MessageBox.Show(result)

    End Sub

End Class

或者，您可以使用VB.NET后期绑定直接调用eval，而不是Document.InvokeScript，这可能更容易编码和阅读：

Public Class Form1

    Private Sub Form1_Load(sender As Object, e As EventArgs) Handles MyBase.Load
        Call WebBrowser1.Navigate("http://example.com")
    End Sub

    Private Sub WebBrowser1_DocumentCompleted(sender As Object, e As WebBrowserDocumentCompletedEventArgs) Handles WebBrowser1.DocumentCompleted

        '
        ' use VB late binding to call eval directly (seamlessly provided by.NET DLR)
        '
        Dim htmlDocument = WebBrowser1.Document.DomDocument
        Dim htmlWindow = htmlDocument.parentWindow
        ' make sure the page has at least one script element, so eval works
        htmlDocument.body.appendChild(htmlDocument.createElement("script"))
        htmlWindow.eval("var anotherDate = new Date('04 Oct 2013 16:04:19').toString()")
        MessageBox.Show(htmlWindow.anotherDate)
        ' the above shows we don't have to use JavaScript anonymous function,
        ' but it's always a good coding style to do so, to scope the context:
        htmlWindow.eval("window.createNewDate = function(){ return new Date().toString(); }")
        MessageBox.Show(htmlWindow.eval("window.createNewDate()"))

        ' we can also mix late binding and InvokeScript
        MessageBox.Show(WebBrowser1.Document.InvokeScript("createNewDate"))

    End Sub

End Class

Answer 2

根据文档，您需要调用客户端中定义的现有脚本：
JavaScript的：

var extDate = new Date("03 Oct 2013 16:04:19");

function test(date) {
  alert(date);
  extDate = date;
}

您也可以调用eval并运行匿名函数。如果您无法控制页面源，这将是首选方法。从本质上讲，您将在JavaScript解释器中调用和运行代码。

C＃：

private void InvokeTestMethod(DateTime date)
{
    if (webBrowser1.Document != null)
    {
        webBrowser1.Document.Body.AppendChild(webBrowser1.Document.CreateElement("script"));
        webBrowser1.Document.InvokeScript("eval", (Object)"(function() { window.date=new Date('03 Oct 2013 16:04:19'); })()");
        webBrowser1.Document.InvokeScript("eval", (Object)"(function() { alert(window.newDate.toString()); })()");
        webBrowser1.Document.InvokeScript("eval", (Object)"(function() { window.date=new Date('" + date.ToString("dd MMM yyyy HH:mm:ss") + "'); })()");
        webBrowser1.Document.InvokeScript("eval", (Object)"(function() { alert(window.newDate.toString()); })()");
    }
}

private void Test()
{
    InvokeTestMethod(DateTime.Now);
}

VB.NET

Private Sub InvokeTestMethod([date] As DateTime)
    If webBrowser1.Document IsNot Nothing Then
        webBrowser1.Document.Body.AppendChild(webBrowser1.Document.CreateElement("script"))
        webBrowser1.Document.InvokeScript("eval", new [Object]() {"(function() { window.date=new Date('03 Oct 2013 16:04:19'); })()"}))
        webBrowser1.Document.InvokeScript("eval", new [Object]() {"(function() { alert(window.newDate.toString()); })()"}))
        webBrowser1.Document.InvokeScript("eval", new [Object]() {"(function() { window.date=new Date('" + [date].ToString("dd MMM yyyy HH:mm:ss") + "'); })()"})
        webBrowser1.Document.InvokeScript("eval", new [Object]() {"(function() { alert(window.newDate.toString()); })()"}))
    End If
End Sub

Private Sub Test()
    InvokeTestMethod(DateTime.Now)
End Sub

http://msdn.microsoft.com/en-us/library/system.windows.forms.htmldocument.invokescript.aspx

通过使用eval，您可以调用anonymous JavaScript函数并在网页的上下文中运行您自己的代码。在最后两次调用eval时，我使用DateTime.Now设置日期，并以JavaScript可以理解的方式格式化日期。

修改WebBrowser控件中的Javascript变量

2 个答案: