消息从外部网页传递到chrome插件

Question

I am trying to make a webpage send data to a chrome extension that will fire when user visit a website(say google here)

manifest.json

{
  "manifest_version": 2,
  "name": "Test Addon",
  "version": "0.01",
  "icons": { "16": "icon-16.ico" },

  "browser_action": {
  "default_icon" : "icon-16.ico",
  "default_popup" : "popup.html"
  },

   "content_scripts": [
    {
      "matches": ["*://*.google.com/*"  ],
      "js": ["cs.js"]
    }
  ],

  "externally_connectable": {
  "matches": ["*://*.mywebsite.com/*"]
}


}

cs.js

chrome.runtime.onMessageExternal.addListener(
  function(request, sender, sendResponse) {
    alert("world");
  });

mywebsite.com/testpage.php

// The ID of my chrome extension (In developer mode)
var editorExtensionId = "cjgeckgdpfhnedenpkaanpehddchlkle";

// Send a message
chrome.runtime.sendMessage("Hello");

</script>

As far as i know content script have access to onMessage and sendMessage but i don't get an alert when i visit google

Answer 1

According to the docs, the extension id should be the first parameter when calling sendMessage(). You simply omitted this param.
The second problem is that messages from external web page can receive only the background script. Check the docs for onMessageExternal().
Use this code to send a message to your background extension script:

// The ID of my chrome extension (In developer mode)
var editorExtensionId = "cjgeckgdpfhnedenpkaanpehddchlkle";

// Send a message
chrome.runtime.sendMessage(editorExtensionId, "Hello");