`CoreWebView2Frame.ExecuteScriptAsync` doesn't seem to do anything

[ppena-LiveData]

Description
Trying to run JavaScript within an <iframe> using CoreWebView2Frame.ExecuteScriptAsync() doesn't seem to do anything.

Version
SDK: 1.0.1466-prerelease
Runtime: 107.0.1418.26 (but probably doesn't matter for this issue)
Framework: WPF (but probably doesn't matter for this issue)
OS: Win11 (but probably doesn't matter for this issue)

Repro Steps
git clone https://github.com/MicrosoftEdge/WebView2Samples.git then apply the below patch and compile and run the WebView2WpfBrowser VS solution:

diff --git a/SampleApps/WebView2WpfBrowser/MainWindow.xaml.cs b/SampleApps/WebView2WpfBrowser/MainWindow.xaml.cs
index e0a9084..c9ac47e 100644
--- a/SampleApps/WebView2WpfBrowser/MainWindow.xaml.cs
+++ b/SampleApps/WebView2WpfBrowser/MainWindow.xaml.cs
@@ -120,6 +120,7 @@ namespace WebView2WpfBrowser
         IReadOnlyList<CoreWebView2ProcessInfo> _processList = new List<CoreWebView2ProcessInfo>();

         public CoreWebView2CreationProperties CreationProperties { get; set; } = null;
+        private WebView2 _webView;

         public MainWindow()
         {
@@ -142,6 +143,7 @@ namespace WebView2WpfBrowser

         void AttachControlEventHandlers(WebView2 control)
         {
+            _webView = control;
             // <NavigationStarting>
             control.NavigationStarting += WebView_NavigationStarting;
             // </NavigationStarting>
@@ -1608,6 +1610,12 @@ namespace WebView2WpfBrowser
         {
             _isNavigating = true;
             RequeryCommands();
+            _webView.ExecuteScriptAsync("window.debugTopLevelProp = 42");
+            _webView.CoreWebView2.FrameCreated += async (object sender1, CoreWebView2FrameCreatedEventArgs args) =>
+            {
+                await args.Frame.ExecuteScriptAsync("alert('this alert is within the frame')");
+                await args.Frame.ExecuteScriptAsync("window.debugFrameProp = 42");
+            };
         }

         void WebView_NavigationCompleted(object sender, CoreWebView2NavigationCompletedEventArgs e)
@@ -1668,7 +1676,7 @@ namespace WebView2WpfBrowser

         private string GetStartPageUri(CoreWebView2 webView2)
         {
-            string uri = "https://appassets.example/AppStartPage.html";
+            string uri = "https://developer.mozilla.org/en-US/docs/Web/HTML/Element/iframe";
             if (webView2 == null)
             {
                 return uri;
diff --git a/SampleApps/WebView2WpfBrowser/WebView2WpfBrowser.csproj b/SampleApps/WebView2WpfBrowser/WebView2WpfBrowser.csproj
index 2ea3c5b..5ef2cde 100644
--- a/SampleApps/WebView2WpfBrowser/WebView2WpfBrowser.csproj
+++ b/SampleApps/WebView2WpfBrowser/WebView2WpfBrowser.csproj
@@ -1,7 +1,7 @@
 <Project Sdk="Microsoft.NET.Sdk.WindowsDesktop">
   <PropertyGroup>
     <OutputType>WinExe</OutputType>
-    <TargetFrameworks>netcoreapp3.0;net462</TargetFrameworks>
+    <TargetFrameworks>netcoreapp3.0;net472</TargetFrameworks>
     <UseWPF>true</UseWPF>
     <Authors>Hybrid Application Team</Authors>
     <Company>Microsoft</Company>
@@ -40,7 +40,7 @@
     </Content>
   </ItemGroup>
   <ItemGroup>
-    <PackageReference Include="Microsoft.Web.WebView2" Version="1.0.1414-prerelease" />
+    <PackageReference Include="Microsoft.Web.WebView2" Version="1.0.1466-prerelease" />
        <PackageReference Include="System.ValueTuple" Version="4.5.0" />
   </ItemGroup>
 </Project>
\ No newline at end of file

I would expect a popup message with this alert is within the frame show up, and using the JS Console in the browser Dev Tools, I would expect window.debugFrameProp to exist within every <iframe>, but in this case, the only thing that exists is window.debugTopLevelProp, at the top level context.

NOTE: I also tried adding an args.Frame.NavigationStarting event handler, but CoreWebView2Frame.ExecuteScriptAsync() also didn't seem to do anything in there.

[victorthoang]

Hello @ppena-LiveData ,

Thanks for your bug report. I've assigned this to a dev that can best try to replicate the issue and follow up on this.

[vbryh-msft]

Hi @ppena-LiveData - this is expected behavior for calling ExecuteScript from FrameCreated event handler - execution context is not yet created at that time. You should call it from ContentLoading or DOMContentLoaded event handlers - here is sample code

Navigation events in webview2 for reference.

[ppena-LiveData]

Thanks for the quick reply.

It's confusing, since args.Frame.AddHostObjectToScript() does work from the FrameCreated event handler. Also, why does it not behave the same as the main window, whose NavigationStarting event handler does work with ExecuteScript calls, but the frame's NavigationStarting event handler does not? Ohhhh, and I just noticed that the ContentLoading event for the main WebView2 says its after "the content of that URI begins to render," whereas the CoreWebView2Frame.ContentLoading says it is "before any content is loaded," so at least two events seem to fire at different times for the WebView2 vs the CoreWebView2Frame.

The Navigation events doc you linked to mentions FrameNavigationStarting and FrameNavigationCompleted events, which are not names of any EventHandler properties that I can find, but maybe it's talking about CoreWebView2Frame.Navigation* events. If so, then the following "Those events act like the equivalent non-frame, counterpart events." sentence is not correct, since ExecuteScript calls work for WebView2 but not for CoreWebView2Frame, so can the documentation be updated?

[vbryh-msft]

• I agree that it is confusing, and we are working on improving documentation.
• Adding host object to script does not require execution context - so that is why it works from frame created event.
• For frame navigation events we have 2 pairs WebView2.FrameNavigationStarting/FrameNavigationCompleted and WebView2Frame.NavigationStarting/NavigationCompleted - they are duplicated, but first one was created when we have not had the frame class planned. So I would suggest to use frame events now.

Please let me know if you have any more questions =)