From 574ac9e8854ff8b471183ceafc07659b2e16b835 Mon Sep 17 00:00:00 2001
From: Eduard Urbach <e.urbach@gmail.com>
Date: Wed, 19 Jul 2017 04:18:56 +0200
Subject: [PATCH] Improved diffs

---
 scripts/AnimeNotifier.ts |  4 ++++
 scripts/Diff.ts          | 19 ++++++++++++++++++-
 2 files changed, 22 insertions(+), 1 deletion(-)

diff --git a/scripts/AnimeNotifier.ts b/scripts/AnimeNotifier.ts
index 759772c5..fbdb4655 100644
--- a/scripts/AnimeNotifier.ts
+++ b/scripts/AnimeNotifier.ts
@@ -30,6 +30,10 @@ export class AnimeNotifier {
 		this.imageNotFound = new MutationQueue(elem => elem.classList.add("image-not-found"))
 		this.unmount = new MutationQueue(elem => elem.classList.remove("mounted"))
 
+		// These classes will never be removed on DOM diffs
+		Diff.persistentClasses.add("mounted")
+		Diff.persistentClasses.add("image-found")
+
 		if("IntersectionObserver" in window) {
 			// Enable lazy load
 			this.visibilityObserver = new IntersectionObserver(
diff --git a/scripts/Diff.ts b/scripts/Diff.ts
index 93c162aa..974a0450 100644
--- a/scripts/Diff.ts
+++ b/scripts/Diff.ts
@@ -1,4 +1,6 @@
 export class Diff {
+	static persistentClasses = new Set<string>()
+
 	// Reuse container for diffs to avoid memory allocation
 	static container: HTMLElement
 
@@ -82,7 +84,22 @@ export class Diff {
 
 					if(attrib.specified) {
 						// Skip mountables
-						if(attrib.name == "class" && (elemA.classList.contains("mounted") || elemA.classList.contains("image-found"))) {
+						if(attrib.name == "class") {
+							let classesA = elemA.classList
+							let classesB = elemB.classList
+
+							for(let className of classesA) {
+								if(!classesB.contains(className) && !Diff.persistentClasses.has(className)) {
+									classesA.remove(className)
+								}
+							}
+
+							for(let className of classesB) {
+								if(!classesA.contains(className)) {
+									classesA.add(className)
+								}
+							}
+
 							continue
 						}