diff --git a/src/console/console.js b/src/console/console.js
index f8a91a6..67b9eab 100644
--- a/src/console/console.js
+++ b/src/console/console.js
@@ -1,41 +1,42 @@
 import './console.scss';
+import * as messages from '../shared/messages';
 
 const parent = window.parent;
 
 // TODO consider object-oriented
 var prevValue = "";
 
-const blurData = () => {
-  return JSON.stringify({
+const blurMessage = () => {
+  return {
     type: 'vimvixen.commandline.blur'
-  });
+  };
 };
 
-const keydownData = (input) => {
-  return JSON.stringify({
+const keydownMessage = (input) => {
+  return {
     type: 'vimvixen.commandline.enter',
     value: input.value
-  });
+  };
 };
 
-const keyupData = (input) => {
-  return JSON.stringify({
+const keyupMessage = (input) => {
+  return {
     type: 'vimvixen.commandline.change',
     value: input.value
-  });
+  };
 };
 
 const handleBlur = () => {
-  parent.postMessage(blurData(), '*');
+  messages.send(parent, blurMessage());
 };
 
 const handleKeydown = (e) => {
   switch(e.keyCode) {
   case KeyboardEvent.DOM_VK_ESCAPE:
-    parent.postMessage(blurData(), '*');
+    messages.send(parent, blurMessage());
     break;
   case KeyboardEvent.DOM_VK_RETURN:
-    parent.postMessage(keydownData(e.target), '*');
+    messages.send(parent, keydownMessage(e.target));
     break;
   }
 };
@@ -44,7 +45,7 @@ const handleKeyup = (e) => {
   if (e.target.value === prevValue) {
     return;
   }
-  parent.postMessage(keyupData(e.target), '*');
+  messages.send(parent, keyupMessage(e.target));
   prevValue = e.target.value;
 };
 
diff --git a/src/content/index.js b/src/content/index.js
index 591aa98..ad3f740 100644
--- a/src/content/index.js
+++ b/src/content/index.js
@@ -1,6 +1,7 @@
 import * as scrolls from './scrolls';
 import * as histories from './histories';
 import * as actions from '../shared/actions';
+import * as messages from '../shared/messages';
 import ConsoleFrame from '../console/console-frame';
 import Follow from './follow';
 
@@ -71,15 +72,7 @@ window.addEventListener("keypress", (e) => {
       });
 });
 
-window.addEventListener('message', (e) => {
-  let message;
-  try {
-    message = JSON.parse(e.data);
-  } catch (e) {
-    // ignore message posted by author of web page
-    return;
-  }
-
+messages.receive(window, (message) => {
   switch (message.type) {
   case 'vimvixen.commandline.blur':
     if (cmd) {
diff --git a/src/shared/messages.js b/src/shared/messages.js
new file mode 100644
index 0000000..517fc4c
--- /dev/null
+++ b/src/shared/messages.js
@@ -0,0 +1,19 @@
+const receive = (win, callback) => {
+  win.addEventListener('message', (e) => {
+    let message;
+    try {
+      message = JSON.parse(e.data);
+    } catch (e) {
+      // ignore message posted by author of web page
+      return;
+    }
+
+    callback(message);
+  })
+}
+
+const send = (win, message) => {
+  win.postMessage(JSON.stringify(message), '*');
+}
+
+export { receive, send };
diff --git a/test/shared/messages.test.js b/test/shared/messages.test.js
new file mode 100644
index 0000000..0ebaf1a
--- /dev/null
+++ b/test/shared/messages.test.js
@@ -0,0 +1,25 @@
+import { expect } from "chai";
+import * as messages from '../../src/shared/messages';
+
+describe('messages', () => {
+  describe('#receive', () => {
+    it('received a message', (done) => {
+      messages.receive(window, (message) => {
+        expect(message).to.deep.equal({ type: 'vimvixen.test' });
+        done();
+      });
+      window.postMessage(JSON.stringify({ type: 'vimvixen.test' }), '*');
+    });
+  });
+
+  describe('#send', () => {
+    it('sends a message', (done) => {
+      window.addEventListener('message', (e) => {
+        let json = JSON.parse(e.data);
+        expect(json).to.deep.equal({ type: 'vimvixen.test' });
+        done();
+      });
+      messages.send(window, { type: 'vimvixen.test' });
+    });
+  });
+});