Chrome扩展程序-获取DOM内容

Question

我正在尝试从弹出窗口访问activeTab DOM内容。这是我的清单：

{
  "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，背景脚本（持久性事件页：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，但对我来说仍然没有意义。

有人可以解释为什么我可能会用另一个。

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);
  });
});

我越来越：

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"
  }
}

content.js

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

popup.html

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

当我运行它时，我仍然遇到相同的错误：

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；我强烈建议您更深入地了解GoogleChrome扩展程序文档 。

关于您的问题，内容脚本或后台页面是不是要走的路：

内容脚本 ：绝对地， 内容脚本是扩展程序中有权访问网页DOM的唯一组件。

后台页面/弹出窗口 ：也许（可能最多两个）之一，您可能需要让内容脚本将DOM内容传递给后台页面或弹出窗口以进行进一步处理。

让我重复一遍，我强烈建议您对可用文档进行更仔细的研究！就是说，这里是一个示例扩展，它检索StackOverflow页面上的DOM内容并将其发送到后台页面，然后在控制台中将其打印出来：

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);
    }
});

manifest.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"]
}