修改JavaScript變量在WebBrowser控件

Question

我有一個網頁是訪問時，使用下面的聲明瞭一個日期變量：

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

該日期，然後在頁面的頂部顯示。有沒有辦法讓我修改該日期變量？ （而不僅僅是可見的HTML源代碼）

我一直在試驗InvokeScript，但是我發現很難理解，如果有人知道並且可以發佈一些與此直接相關的例子，我會非常感激。謝謝。

Answer 1

您可以使用JavaScript的eval注入任何JavaScript代碼，它適用於任何IE版本。你需要確保頁面具有至少一個<script>標籤，不過這很容易：

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，你可以使用VB.NET後期綁定直接調用eval，而不是Document.InvokeScript，這可能更容易編碼和閱讀：

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

根據該文件，你需要調用客戶端定義的現有腳本：
的JavaScript：

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

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

您也可以打電話eval並運行一個匿名函數。如果您無法控制頁面源，這將是首選的方法。從本質上講，您將在JavaScript解釋器中調用和運行代碼。

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

通過使用eval，你可以調用anonymous JavaScript函數和網頁的上下文中運行自己的代碼。在最近兩次對eval的調用中，我使用DateTime.Now設置日期，並以JavaScript可以理解的方式格式化日期。