Version - latest version available on nuget as this post is written.
OS: Win10, Win Server 2012 x64;
.NET 4.5, Any CPU.

I need to run some javascript code when the page loaded. It's nothing complex - just reading some javascript values, serialize more complex objects (JSON.stringify) - or even to use the console.log. Sometimes I open a new tab via javascript. To do this, I added a handler for the DocumentComplete event. Before it worked fine, now it doesn't anymore.

The test was just to read an integer variable or to write something to console and before each call I checked if I am allowed to run the scripts and the property returned always true. How I tried:

1. I tried to use the EvalScript or QueueScriptCall. Blocked;
2. At one moment, I was afraid I was doing some kind of re-entrance locking and I decided to put a timer to schedule the doc-complete handler 2 seconds later. Same effect;
3. I ran the test in a Task object (.net Task) - with the same effect. I checked each time the ManagedThreadId of the event and the one of the thread running the script and they were different;
4. I restarted visual studio and even rebooted the machine - I was thinking there might be a leak somewhere and a resource was blocked. The same effect;
5. I ran it on a relatively clean machine - same.

One thing I noticed: the system window - which contains the browser is still usable (move/minimize/maximize/resize/etc). However, the browser area - while is no longer usable (everything I click does not respond), it's still displayed correctly (there is no whitish layout when an application hangs and no longer responds).

All those tests used to run before - at least a while ago (6-9 months) when I evaluated the library. Sometimes they crashed with an exception saying that the Javascript call is not allowed - which was fine. But now, it just hangs.

So, my question is: is it correct to run javascript code in WebView event's handlers? The one I am mostly interested is DocumentComplete when all data is retrieved. And if not, any reliable way I can do this?

Hi,

Please check the threadings. There are two rules for EO.WebBrowser to function properly:

1. Each WebView is associated to the thread in which it is created. You generally can not call any member method of a WebView from another thread;
2. The thread that the WebView is associated to must continue pumping Windows message. It should never be on a wait block such as waiting for an async task to complete. The WebView's own blocking functions such as EvalScript satisfy this rule by pumping window messages internally;

As such you will definitely run into hangs if you are not careful with async tasks when using WebView. The best practice to evaluate script is to use QueueScriptCall with a complete callback. That function should never block. The callback will be called in the WebView's thread.

If this does not help you resolving the problem, please try to isolate the problem into a test project and send the test project to us. See here for more details:

http://www.essentialobjects.com/forum/test_project.aspx

We will look into it as soon as we have that.

Thanks!

Hi,

Yes. LoadCompleted event is called in the UI thread.

Generally EvalScript should not cause UI issue because the actual JavaScript execution is not done by your UI thread. EvalScript just sends the JavaScript to the browser engine and then runs an internal message loop to wait for the result. However because of its blocking nature, it can cause other issues. So it is best for you to use QueueScriptCall to run the JavaScript asynchronously.

Thanks!

Hi,

Please send the test app to us and we will be happy to take a look. See here for more details:

http://essentialobjects.com/forum/test_project.aspx

Thanks!

Looking forward to! Thanks!

i have a simple form with webView and have javascript code that's below some time a flash screen comes for only mili second and immediately close i record while running this my application and take a screen shot from this video

WebView.EvalScript("document.getElementsByTagName('a').length"))
WebView.EvalScript("document.getElementsByTagName('input')[11"].focus()")
WebView.EvalScript("document.getElementsByTagName('a')[12].click()")
every time this flash comes on different javascript. this flash screen not show all time but mostly it comes
here i am attaching this flash screen
https://postimg.org/image/ij6f8wgnj/

My issue was solved. It works fine now. Thank you.