From 3ea46e531ba4457dc6bee57775b88fc14e903619 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?=E6=9D=8E=E9=B8=BF=E7=AB=A0?= <poodll@163.com>
Date: Fri, 11 Oct 2019 12:01:14 +0800
Subject: [PATCH 1/4] Fix: Scroll sidebar to current active section (#1067)

---
 src/theme/book.js | 10 ++++++----
 1 file changed, 6 insertions(+), 4 deletions(-)

diff --git a/src/theme/book.js b/src/theme/book.js
index 8fda7a6cbe..2fd4a3b52c 100644
--- a/src/theme/book.js
+++ b/src/theme/book.js
@@ -505,10 +505,12 @@ function playpen_text(playpen) {
     }, { passive: true });
 
     // Scroll sidebar to current active section
-    var activeSection = document.getElementById("sidebar").querySelector(".active");
-    if (activeSection) {
-        sidebarScrollBox.scrollTop = activeSection.offsetTop;
-    }
+    window.addEventListener('load', function() {
+        var activeSection = document.getElementById("sidebar").querySelector(".active");
+        if (activeSection) {
+            activeSection.scrollIntoViewIfNeeded();
+        }
+    });
 })();
 
 (function chapterNavigation() {

From db2d574dccc43196a9f9662b2ab8b09d8bcc6938 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?=E6=9D=8E=E9=B8=BF=E7=AB=A0?= <poodll@163.com>
Date: Fri, 11 Oct 2019 14:32:59 +0800
Subject: [PATCH 2/4] Clean: Some code related to PR #1052

---
 src/theme/book.js   | 1 -
 src/theme/index.hbs | 2 +-
 2 files changed, 1 insertion(+), 2 deletions(-)

diff --git a/src/theme/book.js b/src/theme/book.js
index 2fd4a3b52c..09325e1e4c 100644
--- a/src/theme/book.js
+++ b/src/theme/book.js
@@ -408,7 +408,6 @@ function playpen_text(playpen) {
 (function sidebar() {
     var html = document.querySelector("html");
     var sidebar = document.getElementById("sidebar");
-    var sidebarScrollBox = document.querySelector(".sidebar-scrollbox");
     var sidebarLinks = document.querySelectorAll('#sidebar a');
     var sidebarToggleButton = document.getElementById("sidebar-toggle");
     var sidebarResizeHandle = document.getElementById("sidebar-resize-handle");
diff --git a/src/theme/index.hbs b/src/theme/index.hbs
index 8f586e01d1..291e279659 100644
--- a/src/theme/index.hbs
+++ b/src/theme/index.hbs
@@ -87,7 +87,7 @@
         </script>
 
         <nav id="sidebar" class="sidebar" aria-label="Table of contents">
-            <div id="sidebar-scrollbox" class="sidebar-scrollbox">
+            <div class="sidebar-scrollbox">
                 {{#toc}}{{/toc}}
             </div>
             <div id="sidebar-resize-handle" class="sidebar-resize-handle"></div>

From 6864a3e9ca5656c258282e7569ed871501f7030c Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?=E6=9D=8E=E9=B8=BF=E7=AB=A0?= <poodll@163.com>
Date: Sat, 12 Oct 2019 09:43:14 +0800
Subject: [PATCH 3/4] Change `scrollIntoViewIfNeeded` with `scrollIntoView`

---
 src/theme/book.js | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/src/theme/book.js b/src/theme/book.js
index 09325e1e4c..41f6be6287 100644
--- a/src/theme/book.js
+++ b/src/theme/book.js
@@ -507,7 +507,8 @@ function playpen_text(playpen) {
     window.addEventListener('load', function() {
         var activeSection = document.getElementById("sidebar").querySelector(".active");
         if (activeSection) {
-            activeSection.scrollIntoViewIfNeeded();
+            // https://developer.mozilla.org/en-US/docs/Web/API/Element/scrollIntoView
+            activeSection.scrollIntoView({ block: 'center' });
         }
     });
 })();

From f754e376c51a2dbe428e5dd8e6796734cdb33f9c Mon Sep 17 00:00:00 2001
From: Eric Huss <eric@huss.org>
Date: Sun, 8 Mar 2020 21:00:38 -0700
Subject: [PATCH 4/4] Don't use onload event for sidebar scroll to reduce
 flickering.

---
 src/theme/book.js | 12 +++++-------
 1 file changed, 5 insertions(+), 7 deletions(-)

diff --git a/src/theme/book.js b/src/theme/book.js
index 41f6be6287..bd16519cdb 100644
--- a/src/theme/book.js
+++ b/src/theme/book.js
@@ -504,13 +504,11 @@ function playpen_text(playpen) {
     }, { passive: true });
 
     // Scroll sidebar to current active section
-    window.addEventListener('load', function() {
-        var activeSection = document.getElementById("sidebar").querySelector(".active");
-        if (activeSection) {
-            // https://developer.mozilla.org/en-US/docs/Web/API/Element/scrollIntoView
-            activeSection.scrollIntoView({ block: 'center' });
-        }
-    });
+    var activeSection = document.getElementById("sidebar").querySelector(".active");
+    if (activeSection) {
+        // https://developer.mozilla.org/en-US/docs/Web/API/Element/scrollIntoView
+        activeSection.scrollIntoView({ block: 'center' });
+    }
 })();
 
 (function chapterNavigation() {