Javascript 如何将消息从popup.html发送到内容脚本？

我正在进行扩展，希望将消息从popup.html传递到content.js，但是下面的代码警报未定义。请给我一个简单的脚本，将消息从popup.html发送到content.js，反之亦然，我将进一步处理它。我想通过这个扩展访问DOM，以修改和设计网站布局

清单

{
  "manifest_version": 2,
  "name": "Extension",
  "description": "Description",
  "version": "1.0",
  "background": {
   "scripts": ["background.js"],
   "persistent": true
  },
  "content_scripts": [{
    "matches": ["*"],
    "js": ["content.js"]
  }],
  "browser_action": {
   "default_icon": "icons/icon.png",
   "default_popup": "popup.html"
  },
  "permissions":["tabs"]
}

popup.js

document.addEventListener('DOMContentLoaded',function(){

document.getElementById('button').onclick=function(){

    chrome.tabs.query({active: true, currentWindow: true}, function(tabs) {
        chrome.tabs.sendMessage(tabs[0].id, {greeting: "hello"}, function(response) {
            alert(response);
        });
    });

}

});

chrome.runtime.onMessage.addListener(
    function(request, sender, sendResponse) {
        console.log(sender.tab ?
                "from a content script:" + sender.tab.url :
                "from the extension");

        if (request.greeting == "hello")
            sendResponse({farewell: "goodbye"});
});

Content.js

document.addEventListener('DOMContentLoaded',function(){

document.getElementById('button').onclick=function(){

    chrome.tabs.query({active: true, currentWindow: true}, function(tabs) {
        chrome.tabs.sendMessage(tabs[0].id, {greeting: "hello"}, function(response) {
            alert(response);
        });
    });

}

});

chrome.runtime.onMessage.addListener(
    function(request, sender, sendResponse) {
        console.log(sender.tab ?
                "from a content script:" + sender.tab.url :
                "from the extension");

        if (request.greeting == "hello")
            sendResponse({farewell: "goodbye"});
});

试试这个简单的代码

manifest.json

popup.html

content.js

警觉的

---

您的代码对我有效。您是否在此处重新加载了扩展名

chrome://extensions/

？它在警报中返回什么？它警报对象和

警报（response.fore）提醒再见。相信我，此处不起作用。请在回答中跳过相同的代码。这会导致错误“接收端不存在”。也许您没有重新加载页面。看到这个帖子了吗
document.getElementById("set").onclick = function() {

  chrome.tabs.query({active: true, currentWindow: true}, function(tabs) {
        chrome.tabs.sendMessage(tabs[0].id, {greeting: "hello"}, function(response) {
            alert(response.farewell);
        });
    });
}

chrome.runtime.onMessage.addListener(
    function(request, sender, sendResponse) {
        console.log(sender.tab ?
                "from a content script:" + sender.tab.url :
                "from the extension");

        if (request.greeting == "hello")
            sendResponse({farewell: "goodbye"});
});