Issue 4783 - Use Port API for the messageResponder

background.js

Index: background.js
diff --git a/background.js b/background.js
index fa78123054da5bb29352923c3496ec8a049eecde..13fb5aa7f824db5ef3054ca23d443a38cfad3583 100644
--- a/background.js
+++ b/background.js
@@ -337,6 +337,74 @@
     reinitialized: params.filterlistsReinitialized
   };
 
+  let messageListeners = {};
+  modules.messaging = {

[Sebastian Noack, 2017/01/13 12:12:10]

Can you please just use the EventEmitter class here, rather than duplicating the
very same logic?

[kzar, 2017/01/16 04:27:02]

Well I'm not sure I can since the EventEmitter class is defined in
adblockpluschrome not this repository. Unless you mean for me to copy and paste
the whole thing in here?

[Sebastian Noack, 2017/01/16 13:46:38]

See line 20 in this file. There is a class called EventEmitter which you could
use here.

[kzar, 2017/01/16 14:25:56]

Oh yea, sorry I missed that. Done.

+    port: {
+      on: (name, callback) =>
+      {
+        if (!(name in messageListeners))
+          messageListeners[name] = [];
+        messageListeners[name].push(callback);
+      },
+      off: (name, callback) =>
+      {
+        if (!(name in messageListeners))
+          return;
+
+        let index = messageListeners[name].indexOf(callback);
+        if (index == -1)
+          return;
+
+        if (messageListeners[name].length == 1)
+          delete messageListeners[name];
+        else
+          messageListeners[name].splice(index, 1);
+      }
+    }
+  };
+  window.addEventListener("message", event =>
+  {
+    if (event.data.type != "message")
+      return;
+    let message = event.data.payload;
+    let messageId = event.data.messageId;
+    let sender = {
+      page: new ext.Page(event.source)
+    };
+
+    let listeners = messageListeners[message.type];
+    if (!listeners)
+      return;
+
+    function reply(message)
+    {
+      event.source.postMessage({
+        type: "response",
+        messageId: messageId,
+        payload: message
+      }, "*");
+    }
+
+    for (let listener of listeners)
+    {
+      let response = listener(message, sender);
+      if (response && typeof response.then == "function")
+      {
+        response.then(
+          reply,
+          reason => {
+            console.error(reason);
+            reply(undefined);
+          }
+        );
+      }
+      else if (typeof response != "undefined")
+      {
+        reply(response);
+      }
+    }
+  });
+
   global.Services = {
     vc: {
       compare: function(v1, v2)