From 4ba8aea6a106b65ff99dad242d137c792b96a811 Mon Sep 17 00:00:00 2001
From: Dom Christie <christiedom@gmail.com>
Date: Sat, 20 Jul 2024 21:18:51 +0100
Subject: [PATCH] Handle same-page anchor clicks by checking for absence of
 popstate data. Absent popstate event data suggests that the event originates
 from a same-page anchor click. Reconcile the empty state by incrementing the
 History's currentIndex, replacing the null history entry, setting the View's
 lastRenderedLocation, and then caching it

---
 src/core/drive/history.js | 11 +++++++----
 src/core/session.js       | 12 +++++++++++-
 2 files changed, 18 insertions(+), 5 deletions(-)

diff --git a/src/core/drive/history.js b/src/core/drive/history.js
index 569b6a51d..16f11da53 100644
--- a/src/core/drive/history.js
+++ b/src/core/drive/history.js
@@ -78,14 +78,17 @@ export class History {
   // Event handlers
 
   onPopState = (event) => {
-    const { turbo } = event.state || {}
-    if (turbo) {
-      this.location = new URL(window.location.href)
-      const { restorationIdentifier, restorationIndex } = turbo
+    this.location = new URL(window.location.href)
+
+    if (event.state?.turbo) {
+      const { restorationIdentifier, restorationIndex } = event.state.turbo
       this.restorationIdentifier = restorationIdentifier
       const direction = restorationIndex > this.currentIndex ? "forward" : "back"
       this.delegate.historyPoppedToLocationWithRestorationIdentifierAndDirection(this.location, restorationIdentifier, direction)
       this.currentIndex = restorationIndex
+    } else {
+      this.currentIndex++
+      this.delegate.historyPoppedWithEmptyState(this.location)
     }
   }
 }
diff --git a/src/core/session.js b/src/core/session.js
index 1047d4463..1e1ae92ed 100644
--- a/src/core/session.js
+++ b/src/core/session.js
@@ -190,6 +190,10 @@ export class Session {
     }
   }
 
+  historyPoppedWithEmptyState(location) {
+    this.#reconcileEmptyHistoryEntry(location)
+  }
+
   // Scroll observer delegate
 
   scrollPositionChanged(position) {
@@ -233,7 +237,7 @@ export class Session {
   // Navigator delegate
 
   allowsVisitingLocationWithAction(location, action) {
-    return this.locationWithActionIsSamePage(location, action) || this.applicationAllowsVisitingLocation(location)
+    return this.applicationAllowsVisitingLocation(location)
   }
 
   visitProposedToLocation(location, options) {
@@ -469,6 +473,12 @@ export class Session {
   get snapshot() {
     return this.view.snapshot
   }
+
+  #reconcileEmptyHistoryEntry(location) {
+    this.history.replace(location)
+    this.view.lastRenderedLocation = location
+    this.view.cacheSnapshot()
+  }
 }
 
 // Older versions of the Turbo Native adapters referenced the