Can I wait for a webbrowser to finish navigating, using a for loop?
c#, webbrowser-control
Solution
Assuming you host `WebBrowser` in a WinFroms application, you can do it in a loop easily and efficiently, using `async/await` pattern. Try this:
async Task DoNavigationAsync()
{
TaskCompletionSource<bool> tcsNavigation = null;
TaskCompletionSource<bool> tcsDocument = null;
this.WB.Navigated += (s, e) =>
{
if (tcsNavigation.Task.IsCompleted)
return;
tcsNavigation.SetResult(true);
};
this.WB.DocumentCompleted += (s, e) =>
{
if (this.WB.ReadyState != WebBrowserReadyState.Complete)
return;
if (tcsDocument.Task.IsCompleted)
return;
tcsDocument.SetResult(true);
};
for (var i = 0; i <= 21; i++)
{
tcsNavigation = new TaskCompletionSource<bool>();
tcsDocument = new TaskCompletionSource<bool>();
this.WB.Navigate("http://www.example.com?i=" + i.ToString());
await tcsNavigation.Task;
Debug.Print("Navigated: {0}", this.WB.Document.Url);
// navigation completed, but the document may still be loading
await tcsDocument.Task;
Debug.Print("Loaded: {0}", this.WB.DocumentText);
// the document has been fully loaded, you can access DOM here
}
}
Now, it's important to understand that `DoNavigationAsync` executes asynchronously. Here's how you'd call it from `Form_Load` and handle the completion of it:
void Form_Load(object sender, EventArgs e)
{
var task = DoNavigationAsync();
task.ContinueWith((t) =>
{
MessageBox.Show("Navigation done!");
}, TaskScheduler.FromCurrentSynchronizationContext());
}
I've answered a similar question here.
Problem
I have a for loop: ``` for (i = 0; i <= 21; i++) { webB.Navigate(URL); } ``` `webB` is a webBrowser control and `i` is an int. I want to wait for the browser to finish navigating. I found this, however: - I don't want to use any APIs or addins - I can't use another `void` function, as suggested in this answer Is there a way to wait while in a for loop?