I have a webpage that when visited, declares a variable called date using the following:
var date=new Date("03 Oct 2013 16:04:19");
That date is then displayed at the top of the page. Is there a way for me to modify that date variable? (and not just the visible HTML source)
I have been experimenting with InvokeScript but am finding it hard to grasp, if anybody knows and could post some examples relating directly to this I'd be hugely grateful. Thankyou.
You can inject any JavaScript code using JavaScript's eval, it works with any IE version. You'd need to make sure the page has at least one <script> tag, but this is easy:
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
Alternatively, you can use VB.NET late binding to call eval directly, instead of Document.InvokeScript, which might be easier to code and read:
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
eval function. I was going to suggest that too if the OP didn't have access to the source of the webpage.According to the documentation, you need to invoke an existing script defined in the client:
JavaScript:
var extDate = new Date("03 Oct 2013 16:04:19");
function test(date) {
alert(date);
extDate = date;
}
You could also call eval and run an anonymous function. This would be the preferred method if you have no control over the page source. Essentially, you would be invoking and running code in the JavaScript interpreter.
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
By using eval, you can invoke anonymous JavaScript functions and run your own code within the context of the web page. In the last two calls to eval, I set the date using DateTime.Now and format the date in a way that JavaScript can understand.
eval. An empty <script> tag needs to be added first.<script> element to the DOM.
invokeScript()?