Chrome扩展程序的长期连接：从后台检索消息到内容

Question

I read this and searched on other places but I can't solve this issue. I am using long-lived connections. I send a message from content script to background and after that I want to send a message from background to content script. However, I am not able to receive messages on the content file for some reason...

Content script:

var port = chrome.runtime.connect({name: "my-channel"});

// receive messages
port.onMessage.addListener(function(msg) {
  console.log(msg); // doesn't log anything    
});

document.addEventListener('DOMContentLoaded', function () {
    document.getElementById('alertButton').addEventListener('click', function() { 
        // send message
        port.postMessage({myProperty: "value"});
    });
});

Background:

chrome.runtime.onConnect.addListener(function(port) {
    if(port.name == "my-channel"){
        port.onMessage.addListener(function(msg) {
           // do something
           // then send message to the content
           port.postMessage({myProperty: "value"});
        });
    }
});

EDIT: my manifest.json

{
  "manifest_version": 2,
  "name": "Test extension",
  "version": "1.0",
  "browser_action": {
  "default_popup": "main_ui.html",
  "default_title": "Test Extension"
  },
  "content_scripts": [{
    "matches": ["<all_urls>"],
    "js": ["logic.js"]
  }],
  "background": {
    "scripts": ["background.js"],
    "persistent": true
  },
  "permissions": [
    "tabs",
    "activeTab"
  ]
}

Answer 1

solution: I was using an old reference of "port" of when connection happened. The 2nd argument of the listener (that isn't visible there) is actually the port.