Refactor messaging listerners.

src/WidgetMessaging.js

@@ -1,5 +1,5 @@
 /*
-Copyright 2016 OpenMarket Ltd
+Copyright 2017 New Vector Ltd
 
 Licensed under the Apache License, Version 2.0 (the "License");
 you may not use this file except in compliance with the License.
@@ -14,38 +14,12 @@ See the License for the specific language governing permissions and
 limitations under the License.
 */
 
-export default class WidgetMessaging {
-    constructor() {
-        this.listenerCount = 0;
-    }
-
 /**
-     * Register widget message event listeners
+ * Handle widget postMessage events
+ * @param  {Event} event Event to handle
  * @return {undefined}
  */
-    registerListeners() {
+function onMessage(event) {
-        if (this.listenerCount === 0) {
-            window.addEventListener("message", this.onMessage, false);
-        }
-        this.listenerCount += 1;
-    }
-
-    derigisterListeners() {
-        this.listenerCount -= 1;
-        if (this.listenerCount === 0) {
-            window.removeEventListener("message", this.onMessage);
-        }
-        if (this.listenerCount < 0) {
-            // Make an error so we get a stack trace
-            const e = new Error(
-                "WidgetMessaging: mismatched startListening / stopListening detected." +
-                " Negative count",
-            );
-            console.error(e);
-        }
-    }
-
-    onMessage(event) {
     console.warn("Checking for widget event", event);
     if (!event.origin) { // Handle chrome
         event.origin = event.originalEvent.origin;
@@ -60,4 +34,32 @@ export default class WidgetMessaging {
     // TODO -- handle widget actions
     alert(event.data.widgetData);
 }
+
+let listenerCount = 0;
+module.exports = {
+    /**
+     * Register widget message event listeners
+     * @return {undefined}
+     */
+    startListening() {
+        if (listenerCount === 0) {
+            window.addEventListener("message", onMessage, false);
         }
+        listenerCount += 1;
+    },
+
+    stopListening() {
+        listenerCount -= 1;
+        if (listenerCount === 0) {
+            window.removeEventListener("message", onMessage);
+        }
+        if (listenerCount < 0) {
+            // Make an error so we get a stack trace
+            const e = new Error(
+                "WidgetMessaging: mismatched startListening / stopListening detected." +
+                " Negative count",
+            );
+            console.error(e);
+        }
+    },
+};

src/components/views/elements/AppTile.js

@@ -153,8 +153,7 @@ export default React.createClass({
     },
 
     componentWillMount() {
-        this.widgetMessagingClient = new WidgetMessaging();
+        WidgetMessaging.startListening();
-        this.widgetMessagingClient.registerListeners();
         window.addEventListener('message', this._onMessage, false);
         this.setScalarToken();
     },
@@ -207,6 +206,7 @@ export default React.createClass({
     },
 
     componentWillUnmount() {
+        WidgetMessaging.stopListening();
         window.removeEventListener('message', this._onMessage);
     },