From e2c514b781caca33e7e65b3b0032846ded7b3a68 Mon Sep 17 00:00:00 2001
From: Huan Liu <liuhuanjim013@gmail.com>
Date: Mon, 7 Apr 2025 10:29:56 +0800
Subject: [PATCH] fixed nextEpisodeId calculation to use actual indices instead
 of assuming continuous indices

---
 lerobot/templates/visualize_dataset_template.html | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/lerobot/templates/visualize_dataset_template.html b/lerobot/templates/visualize_dataset_template.html
index cf9d40f1..230a8c6f 100644
--- a/lerobot/templates/visualize_dataset_template.html
+++ b/lerobot/templates/visualize_dataset_template.html
@@ -532,7 +532,8 @@
                 btnPause.classList.contains('hidden') ? btnPlay.click() : btnPause.click();
             } else if (key === 'ArrowDown' || key === 'ArrowUp') {
                 const episodes = {{ episodes }};  // Access episodes directly from the Jinja template
-                const nextEpisodeId = key === 'ArrowDown' ? {{ episode_id }} + 1 : {{ episode_id }} - 1;
+                const currentIndex = episodes.indexOf({{ episode_id }});
+                const nextEpisodeId = key === 'ArrowDown' ? episodes.at(currentIndex + 1) : episodes.at(currentIndex - 1);
                 const lowestEpisodeId = episodes.at(0);
                 const highestEpisodeId = episodes.at(-1);
                 if (nextEpisodeId >= lowestEpisodeId && nextEpisodeId <= highestEpisodeId) {