Proof of concept to demonstrate how `tabs.sendMessage` refuses to send in Firefox's responive design mode

README.md

gist-web-extension-onMessage2

Proof of concept to demonstrate how tabs.sendMessage refuses to send in Firefox's responive design mode

Related to: twolfson/livereload-extensions#5

Getting started

Run the following steps to get this proof of concept running:

• Clone the repository

  git clone <repo_url> gist-web-extension-onMessage2
  cd gist-web-extension-onMessage2

• Open Firefox and navigate to about:debugging
• Add our extension as a temporary add-on
• Open its "Debug" console
• Navigate to a normal website (e.g. https://mozilla.org/)
• Open our in-page Developer console
• Click our icon, look at "Debug" console, and verify message sending
• Look at our in-page Developer console and verify message logged
• Enter Responsive Design Mode
• Click our icon, look at "Debug" console, and verify message failing to send
• Look at our in-page Developer console and verify no message logged

global.js

browser.browserAction.onClicked.addListener(function handleAddListener(tab) {
  console.log('Sending message to...', tab.id);
  browser.tabs.sendMessage(tab.id, 'Hello World!');
});

IconDisabled.png

injected.js

browser.runtime.onMessage.addListener(function handleMessage (message, sender, sendResponse) {
  console.log('Received message: ', message);
});

manifest.json

{
  "manifest_version": 2,
  "name": "gist-web-extension-onMessage2",
  "version": "1.0.0",
  "background": {
    "scripts": [
      "global.js"
    ]
  },
  "content_scripts": [
    {
      "matches": ["<all_urls>"],
      "js": ["injected.js"]
    }
  ],
  "web_accessible_resources": [],
  "permissions": [
    "tabs",
    "<all_urls>"
  ],
  "browser_action": {
    "default_title": "Enable extension",
    "default_icon": "IconDisabled.png"
  }
}