3 files changed, 57 insertions, 49 deletions

diff --git a/ext/mixed/js/core.js b/ext/mixed/js/core.js
index b6ecb48b..330a30fb 100644
--- a/ext/mixed/js/core.js
+++ b/ext/mixed/js/core.js
@@ -236,6 +236,29 @@ class EventDispatcher {
     }
 }
 
+class EventListenerCollection {
+    constructor() {
+        this._eventListeners = [];
+    }
+
+    get size() {
+        return this._eventListeners.length;
+    }
+
+    addEventListener(node, type, listener, options) {
+        node.addEventListener(type, listener, options);
+        this._eventListeners.push([node, type, listener, options]);
+    }
+
+    removeAllEventListeners() {
+        if (this._eventListeners.length === 0) { return; }
+        for (const [node, type, listener, options] of this._eventListeners) {
+            node.removeEventListener(type, listener, options);
+        }
+        this._eventListeners = [];
+    }
+}
+
 
 /*
  * Default message handlers
diff --git a/ext/mixed/js/display.js b/ext/mixed/js/display.js
index e914b082..8113260c 100644
--- a/ext/mixed/js/display.js
+++ b/ext/mixed/js/display.js
@@ -35,8 +35,8 @@ class Display {
         this.audioCache = new Map();
         this.styleNode = null;
 
-        this.eventListeners = [];
-        this.persistentEventListeners = [];
+        this.eventListeners = new EventListenerCollection();
+        this.persistentEventListeners = new EventListenerCollection();
         this.interactive = false;
         this.eventListenersActive = false;
         this.clickScanPrevent = false;
@@ -301,13 +301,23 @@ class Display {
         this.interactive = interactive;
 
         if (interactive) {
-            Display.addEventListener(this.persistentEventListeners, document, 'keydown', this.onKeyDown.bind(this), false);
-            Display.addEventListener(this.persistentEventListeners, document, 'wheel', this.onWheel.bind(this), {passive: false});
-            Display.addEventListener(this.persistentEventListeners, document.querySelector('.action-previous'), 'click', this.onSourceTermView.bind(this));
-            Display.addEventListener(this.persistentEventListeners, document.querySelector('.action-next'), 'click', this.onNextTermView.bind(this));
-            Display.addEventListener(this.persistentEventListeners, document.querySelector('.navigation-header'), 'wheel', this.onHistoryWheel.bind(this), {passive: false});
+            const actionPrevious = document.querySelector('.action-previous');
+            const actionNext = document.querySelector('.action-next');
+            const navigationHeader = document.querySelector('.navigation-header');
+
+            this.persistentEventListeners.addEventListener(document, 'keydown', this.onKeyDown.bind(this), false);
+            this.persistentEventListeners.addEventListener(document, 'wheel', this.onWheel.bind(this), {passive: false});
+            if (actionPrevious !== null) {
+                this.persistentEventListeners.addEventListener(actionPrevious, 'click', this.onSourceTermView.bind(this));
+            }
+            if (actionNext !== null) {
+                this.persistentEventListeners.addEventListener(actionNext, 'click', this.onNextTermView.bind(this));
+            }
+            if (navigationHeader !== null) {
+                this.persistentEventListeners.addEventListener(navigationHeader, 'wheel', this.onHistoryWheel.bind(this), {passive: false});
+            }
         } else {
-            Display.clearEventListeners(this.persistentEventListeners);
+            this.persistentEventListeners.removeAllEventListeners();
         }
         this.setEventListenersActive(this.eventListenersActive);
     }
@@ -318,23 +328,23 @@ class Display {
         this.eventListenersActive = active;
 
         if (active) {
-            this.addEventListeners('.action-add-note', 'click', this.onNoteAdd.bind(this));
-            this.addEventListeners('.action-view-note', 'click', this.onNoteView.bind(this));
-            this.addEventListeners('.action-play-audio', 'click', this.onAudioPlay.bind(this));
-            this.addEventListeners('.kanji-link', 'click', this.onKanjiLookup.bind(this));
+            this.addMultipleEventListeners('.action-add-note', 'click', this.onNoteAdd.bind(this));
+            this.addMultipleEventListeners('.action-view-note', 'click', this.onNoteView.bind(this));
+            this.addMultipleEventListeners('.action-play-audio', 'click', this.onAudioPlay.bind(this));
+            this.addMultipleEventListeners('.kanji-link', 'click', this.onKanjiLookup.bind(this));
             if (this.options.scanning.enablePopupSearch) {
-                this.addEventListeners('.term-glossary-item, .tag', 'mouseup', this.onGlossaryMouseUp.bind(this));
-                this.addEventListeners('.term-glossary-item, .tag', 'mousedown', this.onGlossaryMouseDown.bind(this));
-                this.addEventListeners('.term-glossary-item, .tag', 'mousemove', this.onGlossaryMouseMove.bind(this));
+                this.addMultipleEventListeners('.term-glossary-item, .tag', 'mouseup', this.onGlossaryMouseUp.bind(this));
+                this.addMultipleEventListeners('.term-glossary-item, .tag', 'mousedown', this.onGlossaryMouseDown.bind(this));
+                this.addMultipleEventListeners('.term-glossary-item, .tag', 'mousemove', this.onGlossaryMouseMove.bind(this));
             }
         } else {
-            Display.clearEventListeners(this.eventListeners);
+            this.eventListeners.removeAllEventListeners();
         }
     }
 
-    addEventListeners(selector, type, listener, options) {
+    addMultipleEventListeners(selector, type, listener, options) {
         for (const node of this.container.querySelectorAll(selector)) {
-            Display.addEventListener(this.eventListeners, node, type, listener, options);
+            this.eventListeners.addEventListener(node, type, listener, options);
         }
     }
 
@@ -793,19 +803,6 @@ class Display {
         return -1;
     }
 
-    static addEventListener(eventListeners, object, type, listener, options) {
-        if (object === null) { return; }
-        object.addEventListener(type, listener, options);
-        eventListeners.push([object, type, listener, options]);
-    }
-
-    static clearEventListeners(eventListeners) {
-        for (const [object, type, listener, options] of eventListeners) {
-            object.removeEventListener(type, listener, options);
-        }
-        eventListeners.length = 0;
-    }
-
     static getElementTop(element) {
         const elementRect = element.getBoundingClientRect();
         const documentRect = document.documentElement.getBoundingClientRect();
diff --git a/ext/mixed/js/text-scanner.js b/ext/mixed/js/text-scanner.js
index e6da1e5e..aa10bbaf 100644
--- a/ext/mixed/js/text-scanner.js
+++ b/ext/mixed/js/text-scanner.js
@@ -31,7 +31,7 @@ class TextScanner {
         this.options = null;
 
         this.enabled = false;
-        this.eventListeners = [];
+        this.eventListeners = new EventListenerCollection();
 
         this.primaryTouchIdentifier = null;
         this.preventNextContextMenu = false;
@@ -229,7 +229,7 @@ class TextScanner {
             }
         } else {
             if (this.enabled) {
-                this.clearEventListeners();
+                this.eventListeners.removeAllEventListeners();
                 this.enabled = false;
             }
             this.onSearchClear(false);
@@ -237,13 +237,13 @@ class TextScanner {
     }
 
     hookEvents() {
-        let eventListeners = this.getMouseEventListeners();
+        let eventListenerInfos = this.getMouseEventListeners();
         if (this.options.scanning.touchInputEnabled) {
-            eventListeners = eventListeners.concat(this.getTouchEventListeners());
+            eventListenerInfos = eventListenerInfos.concat(this.getTouchEventListeners());
         }
 
-        for (const [node, type, listener, options] of eventListeners) {
-            this.addEventListener(node, type, listener, options);
+        for (const [node, type, listener, options] of eventListenerInfos) {
+            this.eventListeners.addEventListener(node, type, listener, options);
         }
     }
 
@@ -268,18 +268,6 @@ class TextScanner {
         ];
     }
 
-    addEventListener(node, type, listener, options) {
-        node.addEventListener(type, listener, options);
-        this.eventListeners.push([node, type, listener, options]);
-    }
-
-    clearEventListeners() {
-        for (const [node, type, listener, options] of this.eventListeners) {
-            node.removeEventListener(type, listener, options);
-        }
-        this.eventListeners = [];
-    }
-
     setOptions(options) {
         this.options = options;
         this.setEnabled(this.options.general.enable);