Fix fetch request in data-enhance-nav="false" for same-page anchors

src/Components/Web.JS/src/Services/NavigationEnhancement.ts

@@ -2,7 +2,7 @@
 // The .NET Foundation licenses this file to you under the MIT license.
 
 import { synchronizeDomContent } from '../Rendering/DomMerging/DomSync';
-import { attachProgrammaticEnhancedNavigationHandler, handleClickForNavigationInterception, hasInteractiveRouter, isForSamePath, isSamePageWithHash, notifyEnhancedNavigationListeners, performScrollToElementOnTheSamePage } from './NavigationUtils';
+import { attachProgrammaticEnhancedNavigationHandler, handleClickForNavigationInterception, hasInteractiveRouter, isForSamePath, isSamePageWithHash, notifyEnhancedNavigationListeners, performScrollToElementOnTheSamePage, isHashOnlyChange } from './NavigationUtils';
 import { resetScrollAfterNextBatch, resetScrollIfNeeded } from '../Rendering/Renderer';
 
 /*
@@ -120,6 +120,10 @@ function onPopState(state: PopStateEvent) {
     return;
   }
 
+  if (isHashOnlyChange(currentContentUrl, location.href)){
+    return;
+  }
+
   // load the new page
   performEnhancedPageLoad(location.href, /* interceptedLink */ false);
 }

src/Components/Web.JS/src/Services/NavigationUtils.ts

@@ -52,6 +52,17 @@ export function isSamePageWithHash(absoluteHref: string): boolean {
   return url.hash !== '' && location.origin === url.origin && location.pathname === url.pathname && location.search === url.search;
 }
 
+export function isHashOnlyChange(oldUrl: string, newUrl: string): boolean {
+  try {
+    const a = new URL(oldUrl);
+    const b = new URL(newUrl);
+    return a.origin === b.origin && a.pathname === b.pathname
+      && a.search === b.search && a.hash !== b.hash;
+  } catch {
+    return false;
+  }
+}
+
 export function isForSamePath(url1: string, url2: string) {
   // We are going to use the scheme, host, port and path to determine if the two URLs are compatible.
   // We do not account for the query string as we want to allow for the query string to change.

src/Components/test/E2ETest/ServerRenderingTests/EnhancedNavigationTest.cs

@@ -10,6 +10,7 @@
 using Microsoft.AspNetCore.InternalTesting;
 using OpenQA.Selenium;
 using OpenQA.Selenium.BiDi.Communication;
+using OpenQA.Selenium.DevTools;
 using OpenQA.Selenium.Support.Extensions;
 using TestServer;
 using Xunit.Abstractions;
@@ -195,6 +196,34 @@ public void CanScrollToHashWithoutPerformingFullNavigation()
             .EndsWith("scroll-to-hash", StringComparison.Ordinal));
     }
 
+    [Fact]
+    public void NonEnhancedNavCanScrollToHashWithoutFetchingPage()
+    {
+        Navigate($"{ServerPathBase}/nav/scroll-to-hash");
+        Browser.Equal("Scroll to hash", () => Browser.Exists(By.TagName("h1")).Text);
+
+        var javascript = (IJavaScriptExecutor)Browser;
+        javascript.ExecuteScript(@"
+            window.testFetchCalls = [];
+            const originalFetch = window.fetch;
+            window.fetch = function(...args) {
+                window.testFetchCalls.push(args[0]);
+                return originalFetch.apply(this, args);
+                };");
+
+        Browser.Exists(By.Id("scroll-anchor-enhance-nav-false")).Click();
+        Browser.True(() => Browser.GetScrollY() > 500);
+        Browser.True(() => Browser
+            .Exists(By.Id("uri-on-page-load-enhance-nav-false"))
+            .GetDomAttribute("data-value")
+            .EndsWith("scroll-to-hash", StringComparison.Ordinal));
+
+        var fetchCalls = javascript.ExecuteScript("return window.testFetchCalls;") as IEnumerable<object>;
+        var relevantCalls = fetchCalls?.Where(call => call.ToString().Contains("scroll-to-hash")) ?? Enumerable.Empty<object>();
+
+        Assert.Empty(relevantCalls);
+    }
+
     [Theory]
     [InlineData("server")]
     [InlineData("webassembly")]

src/Components/test/testassets/Components.TestServer/RazorComponents/Pages/EnhancedNav/PageForScrollingToHash.razor

@@ -13,6 +13,11 @@
     <div id="uri-on-page-load" style="display: none" data-value="@uriOnPageLoad"></div>
 </p>
 
+<p data-enhance-nav="false">
+    <a id="scroll-anchor-enhance-nav-false" href="nav/scroll-to-hash#some-content">Scroll via anchor</a>
+    <div id="uri-on-page-load-enhance-nav-false" style="display: none" data-value="@uriOnPageLoad"></div>
+</p>
+
 <div style="height: 2000px; border: 2px dashed red;">spacer</div>
 
 @if (showContent)