From 4a76c1280399ca6c8802063e6394b30a9af137a3 Mon Sep 17 00:00:00 2001
From: Eduard Urbach <e.urbach@gmail.com>
Date: Wed, 5 Jul 2017 21:06:38 +0200
Subject: [PATCH] Added mutation queues

---
 scripts/AnimeNotifier.ts | 23 ++++++++++++++++-------
 scripts/Diff.ts          | 22 +++++++++++++++-------
 scripts/MutationQueue.ts | 29 +++++++++++++++++++++++++++++
 3 files changed, 60 insertions(+), 14 deletions(-)
 create mode 100644 scripts/MutationQueue.ts

diff --git a/scripts/AnimeNotifier.ts b/scripts/AnimeNotifier.ts
index 32b374e5..fdaf4364 100644
--- a/scripts/AnimeNotifier.ts
+++ b/scripts/AnimeNotifier.ts
@@ -2,17 +2,26 @@ import { Application } from "./Application"
 import { Diff } from "./Diff"
 import { displayLocalDate } from "./DateView"
 import { findAll, delay } from "./Utils"
+import { MutationQueue } from "./MutationQueue"
 import * as actions from "./Actions"
 
 export class AnimeNotifier {
 	app: Application
-	visibilityObserver: IntersectionObserver
 	user: HTMLElement
+	visibilityObserver: IntersectionObserver
+
+	imageFound: MutationQueue
+	imageNotFound: MutationQueue
+	unmount: MutationQueue
 
 	constructor(app: Application) {
 		this.app = app
 		this.user = null
 
+		this.imageFound = new MutationQueue(elem => elem.classList.add("image-found"))
+		this.imageNotFound = new MutationQueue(elem => elem.classList.add("image-not-found"))
+		this.unmount = new MutationQueue(elem => elem.classList.remove("mounted"))
+
 		if("IntersectionObserver" in window) {
 			// Enable lazy load
 			this.visibilityObserver = new IntersectionObserver(
@@ -185,15 +194,15 @@ export class AnimeNotifier {
 			img.src = img.dataset.src
 
 			if(img.naturalWidth === 0) {
-				img.onload = function() {
-					this.classList.add("image-found")
+				img.onload = () => {
+					this.imageFound.queue(img)
 				}
 
-				img.onerror = function() {
-					this.classList.add("image-not-found")
+				img.onerror = () => {
+					this.imageNotFound.queue(img)
 				}
 			} else {
-				img.classList.add("image-found")
+				this.imageFound.queue(img)
 			}
 		}
 
@@ -210,7 +219,7 @@ export class AnimeNotifier {
 				continue
 			}
 
-			element.classList.remove("mounted")
+			this.unmount.queue(element)
 		}
 	}
 
diff --git a/scripts/Diff.ts b/scripts/Diff.ts
index 342e8186..2326bf50 100644
--- a/scripts/Diff.ts
+++ b/scripts/Diff.ts
@@ -1,4 +1,18 @@
 export class Diff {
+	// Reuse container for diffs to avoid memory allocation
+	static container: HTMLElement
+
+	// innerHTML will diff the element with the given HTML string and apply DOM mutations.
+	static innerHTML(aRoot: HTMLElement, html: string) {
+		if(!Diff.container) {
+			Diff.container = document.createElement("main")
+		}
+		
+		Diff.container.innerHTML = html
+		Diff.childNodes(aRoot, Diff.container)
+	}
+
+	// childNodes diffs the child nodes of 2 given elements and applies DOM mutations.
 	static childNodes(aRoot: Node, bRoot: Node) {
 		let aChild = [...aRoot.childNodes]
 		let bChild = [...bRoot.childNodes]
@@ -33,6 +47,7 @@ export class Diff {
 				let elemA = a as HTMLElement
 				let elemB = b as HTMLElement
 
+				// Skip iframes
 				if(elemA.tagName === "IFRAME") {
 					continue
 				}
@@ -75,11 +90,4 @@ export class Diff {
 			Diff.childNodes(a, b)
 		}
 	}
-
-	static innerHTML(aRoot: HTMLElement, html: string) {
-		let bRoot = document.createElement("main")
-		bRoot.innerHTML = html
-		
-		Diff.childNodes(aRoot, bRoot)
-	}
 }
\ No newline at end of file
diff --git a/scripts/MutationQueue.ts b/scripts/MutationQueue.ts
new file mode 100644
index 00000000..b353ab59
--- /dev/null
+++ b/scripts/MutationQueue.ts
@@ -0,0 +1,29 @@
+export class MutationQueue {
+	elements: Array<HTMLElement>
+	mutation: (elem: HTMLElement) => void
+
+	constructor(mutation: (elem: HTMLElement) => void) {
+		this.mutation = mutation
+		this.elements = []
+	}
+
+	queue(elem: HTMLElement) {
+		this.elements.push(elem)
+
+		if(this.elements.length === 1) {
+			window.requestAnimationFrame(() => this.mutateAll())
+		}
+	}
+
+	mutateAll() {
+		for(let i = 0; i < this.elements.length; i++) {
+			this.mutation(this.elements[i])
+		}
+
+		this.clear()
+	}
+
+	clear() {
+		this.elements.length = 0
+	}
+}
\ No newline at end of file