Don't intercept clicks for links that open in external frames #1352 (#1354)

src/Microsoft.AspNetCore.Blazor.Browser.JS/src/Services/UriHelper.ts

@@ -27,9 +27,11 @@ function enableNavigationInterception(assemblyName: string, functionName: string
     if (anchorTarget && anchorTarget.hasAttribute(hrefAttributeName) && event.button === 0) {
       const href = anchorTarget.getAttribute(hrefAttributeName)!;
       const absoluteHref = toAbsoluteUri(href);
+      const targetAttributeValue = anchorTarget.getAttribute('target');
+      const opensInSameFrame = !targetAttributeValue || targetAttributeValue === '_self';
 
       // Don't stop ctrl/meta-click (etc) from opening links in new tabs/windows
-      if (isWithinBaseUriSpace(absoluteHref) && !eventHasSpecialKey(event)) {
+      if (isWithinBaseUriSpace(absoluteHref) && !eventHasSpecialKey(event) && opensInSameFrame) {
         event.preventDefault();
         performInternalNavigation(absoluteHref);
       }

test/Microsoft.AspNetCore.Blazor.E2ETest/Tests/RoutingTest.cs

@@ -117,6 +117,34 @@ namespace Microsoft.AspNetCore.Blazor.E2ETest.Tests
             }
         }
 
+        [Fact]
+        public void CanFollowLinkToTargetBlankClick()
+        {
+            try
+            {
+                SetUrlViaPushState("/");
+
+                var app = MountTestComponent<TestRouter>(); 
+
+                app.FindElement(By.LinkText("Target (_blank)")).Click();
+
+                WaitAssert.Equal(2, () => Browser.WindowHandles.Count);
+            }
+            finally
+            {
+                // Closing newly opened windows if a new one was opened
+                while (Browser.WindowHandles.Count > 1)
+                {
+                    Browser.SwitchTo().Window(Browser.WindowHandles.Last());
+                    Browser.Close();
+                }
+
+                // Needed otherwise Selenium tries to direct subsequent commands
+                // to the tab that has already been closed
+                Browser.SwitchTo().Window(Browser.WindowHandles.First());
+            }
+        }
+
         [Fact]
         public void CanFollowLinkToOtherPageDoesNotOpenNewWindow()
         {

test/testapps/BasicTestApp/RouterTest/Links.cshtml

@@ -20,3 +20,5 @@
 <a id="anchor-with-no-href">
     Anchor tag with no href attribute
 </a>
+
+<a href="/" target="_blank">Target (_blank)</a>