From 1d2a91523604cce7dd608408da65bea5645fc7d4 Mon Sep 17 00:00:00 2001
From: James Maa <jmaa@berkeley.edu>
Date: Sun, 16 Jun 2024 18:39:44 -0700
Subject: Fix DOMTextScanner entering initial div on backwards seeks (#1071)

* Fix dom-text-scanner entering initial div on reverse seeks

* Add new case

* Add launch.json

* Cleanup launch.json
---
 ext/js/dom/dom-text-scanner.js | 7 +++++++
 1 file changed, 7 insertions(+)

(limited to 'ext/js/dom')

diff --git a/ext/js/dom/dom-text-scanner.js b/ext/js/dom/dom-text-scanner.js
index eb56baf9..5325b894 100644
--- a/ext/js/dom/dom-text-scanner.js
+++ b/ext/js/dom/dom-text-scanner.js
@@ -36,6 +36,8 @@ export class DOMTextScanner {
         const resetOffset = (ruby !== null);
         if (resetOffset) { node = ruby; }
 
+        /** @type {Node} */
+        this._initialNode = node;
         /** @type {Node} */
         this._node = node;
         /** @type {number} */
@@ -129,11 +131,16 @@ export class DOMTextScanner {
                 }
             } else if (nodeType === ELEMENT_NODE) {
                 lastNode = node;
+                const initialNodeAtBeginningOfNodeGoingBackwards = node === this._initialNode && this._offset === 0 && !forward;
+                const initialNodeAtEndOfNodeGoingForwards = node === this._initialNode && this._offset === node.childNodes.length && forward;
                 this._offset = 0;
                 ({enterable, newlines} = DOMTextScanner.getElementSeekInfo(/** @type {Element} */ (node)));
                 if (newlines > this._newlines && generateLayoutContent) {
                     this._newlines = newlines;
                 }
+                if (initialNodeAtBeginningOfNodeGoingBackwards || initialNodeAtEndOfNodeGoingForwards) {
+                    enterable = false;
+                }
             }
 
             /** @type {Node[]} */
-- 
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