javascript - Chrome 扩展 - 获取 DOM 内容

Question

我正在尝试从我的弹出窗口访问 activeTab DOM 内容。这是我的 list :

{
  "manifest_version": 2,

  "name": "Test",
  "description": "Test script",
  "version": "0.1",

  "permissions": [
    "activeTab",
    "https://api.domain.com/"
  ],

  "background": {
    "scripts": ["background.js"],
    "persistent": false
  },
  "content_security_policy": "script-src 'self' 'unsafe-eval'; object-src 'self'",

  "browser_action": {
    "default_icon": "icon.png",
    "default_title": "Chrome Extension test",
    "default_popup": "index.html"
  }
}

我真的很困惑后台脚本(具有持久性的事件页面:false)还是 content_scripts 是可行的方法。我已经阅读了所有文档和其他 SO 帖子，但对我来说仍然毫无意义。

谁能解释为什么我可能会使用其中一个。

这是我一直在尝试的 background.js:

chrome.extension.onMessage.addListener(
  function(request, sender, sendResponse) {
    // LOG THE CONTENTS HERE
    console.log(request.content);
  }
);

我只是从弹出控制台执行此操作:

chrome.tabs.getSelected(null, function(tab) {
  chrome.tabs.sendMessage(tab.id, { }, function(response) {
    console.log(response);
  });
});

我得到:

Port: Could not establish connection. Receiving end does not exist. 

更新:

{
  "manifest_version": 2,

  "name": "test",
  "description": "test",
  "version": "0.1",

  "permissions": [
    "tabs",
    "activeTab",
    "https://api.domain.com/"
  ],

  "content_scripts": [
    {
      "matches": ["<all_urls>"],
      "js": ["content.js"]
    }
  ],

  "content_security_policy": "script-src 'self' 'unsafe-eval'; object-src 'self'",

  "browser_action": {
    "default_icon": "icon.png",
    "default_title": "Test",
    "default_popup": "index.html"
  }
}

内容.js

chrome.extension.onMessage.addListener(
  function(request, sender, sendResponse) {
    if (request.text && (request.text == "getDOM")) {
      sendResponse({ dom: document.body.innerHTML });
    }
  }
);

弹出窗口

chrome.tabs.getSelected(null, function(tab) {
  chrome.tabs.sendMessage(tab.id, { action: "getDOM" }, function(response) {
    console.log(response);
  });
});

当我运行它时，我仍然得到同样的错误:

undefined
Port: Could not establish connection. Receiving end does not exist. lastError:30
undefined

Answer 1

术语“背景页面”、“弹出窗口”、“内容脚本”仍然让您感到困惑；我强烈建议更深入地了解 Google Chrome Extensions Documentation .

关于您的问题，内容脚本或背景页面是否可行:

内容脚本:绝对
内容脚本是扩展程序中唯一可以访问网页 DOM 的组件。

背景页面/弹出窗口:可能(可能最多两者之一)
您可能需要让内容脚本将 DOM 内容传递到后台页面或弹出窗口以进行进一步处理。

---

我再说一遍，我强烈建议您更仔细地研究可用的文档!
也就是说，这是一个示例扩展，它检索 StackOverflow 页面上的 DOM 内容并将其发送到后台页面，后台页面又将其打印在控制台中:

background.js:

// Regex-pattern to check URLs against. 
// It matches URLs like: http[s]://[...]stackoverflow.com[...]
var urlRegex = /^https?:\/\/(?:[^./?#]+\.)?stackoverflow\.com/;

// A function to use as callback
function doStuffWithDom(domContent) {
    console.log('I received the following DOM content:\n' + domContent);
}

// When the browser-action button is clicked...
chrome.browserAction.onClicked.addListener(function (tab) {
    // ...check the URL of the active tab against our pattern and...
    if (urlRegex.test(tab.url)) {
        // ...if it matches, send a message specifying a callback too
        chrome.tabs.sendMessage(tab.id, {text: 'report_back'}, doStuffWithDom);
    }
});

content.js:

// Listen for messages
chrome.runtime.onMessage.addListener(function (msg, sender, sendResponse) {
    // If the received message has the expected format...
    if (msg.text === 'report_back') {
        // Call the specified callback, passing
        // the web-page's DOM content as argument
        sendResponse(document.all[0].outerHTML);
    }
});

list .json:

{
  "manifest_version": 2,
  "name": "Test Extension",
  "version": "0.0",
  ...

  "background": {
    "persistent": false,
    "scripts": ["background.js"]
  },
  "content_scripts": [{
    "matches": ["*://*.stackoverflow.com/*"],
    "js": ["content.js"]
  }],
  "browser_action": {
    "default_title": "Test Extension"
  },

  "permissions": ["activeTab"]
}