使用 Chrome 扩展程序更改 navigator.userAgent [英] Changing navigator.userAgent using Chrome Extension

问题描述

我正在尝试使用简单的 chrome 扩展重载 navigator.userAgent.由于内容脚本在隔离的环境中运行，我尝试创建一个脚本元素并将逻辑写入这个元素.这发生在扩展程序的后台页面

I am trying to overload the navigator.userAgent using a simple chrome extension. As the content scripts operate in isolated env, I tried to create a script element and write the logic into this one. This happens from background page of the extension

chrome.tabs.query({
  active:!0
}, function(tabs) {
    var x = "window.navigator.__defineGetter__('userAgent', function() {" +
            "return 'Mozilla/5.0 (Linux; Android 4.2.1; en-us; Nexus 5 Build/JOP40D)" +
            " AppleWebKit/535.19 (KHTML, like Gecko) Chrome/18.0.1025.166 Mobile " + 
            "Safari/535.19'; });console.log(navigator.userAgent);";

    for (var i = 0;i < tabs.length;i++) {
      var code = 'var s = document.createElement("script"); s.text = "' + x +
                 '"; document.head.insertBefore(s, document.head.firstChild);' + 
                 'navigator.userAgent ="s"; console.log(navigator.userAgent);';

      // Inject into the tabs of choice - currently everything.
      chrome.tabs.executeScript(tabs[i].id, {
        code: code
      });
    }
  });

脚本被附加到 head 元素，我可以看到 UA 字符串是通过在 chrome 的控制台中尝试 navigator.userAgent 来欺骗的，因此我相信导航器对象已重载.

The script gets appended for the head element and I can see that the UA string as the one that is spoofed by trying navigator.userAgent in the console of the chrome and so I believe that the navigator object was overloaded.

但这似乎不是有效的方法或根本没有发生，因为导航器对象没有更新，我是通过 - http://www.quirksmode.org/js/detect.html 仍然显示 Mac 的 UA.

But this seems to be not the effective way or not happening at all as the navigator object was not updated which I found out via - http://www.quirksmode.org/js/detect.html which still shows the UA for Mac.

那么，我到底错过了什么?

So, what exactly am I missing here?

推荐答案

navigator.userAgent 是只读属性.如果要更改navigator.userAgent，则需要创建一个新对象并复制属性，或者创建一个新对象并从navigator 继承并分配一个新对象吸气剂/吸气剂.

navigator.userAgent is a read-only property. If you want to change navigator.userAgent, then you need to either create a new object and copy the properties, or create a new object and inherit from navigator and assign a new getter/setter.

我最近创建了这样的扩展.我使用的是 Linux，但我偶尔会下载 Windows 版 Chrome.以下扩展程序将 Chrome 下载页面上的用户代理更改为 Windows XP:

I've recently created such an extension. I'm on Linux, though I occasionally download the Chrome for Windows. The following extension changes the user agent to Windows XP on Chrome's download page:

var actualCode =  '(' + function() {
    'use strict';
    var navigator = window.navigator;
    var modifiedNavigator;
    if ('userAgent' in Navigator.prototype) {
        // Chrome 43+ moved all properties from navigator to the prototype,
        // so we have to modify the prototype instead of navigator.
        modifiedNavigator = Navigator.prototype;

    } else {
        // Chrome 42- defined the property on navigator.
        modifiedNavigator = Object.create(navigator);
        Object.defineProperty(window, 'navigator', {
            value: modifiedNavigator,
            configurable: false,
            enumerable: false,
            writable: false
        });
    }
    // Pretend to be Windows XP
    Object.defineProperties(modifiedNavigator, {
        userAgent: {
            value: navigator.userAgent.replace(/([^)]+)/, 'Windows NT 5.1'),
            configurable: false,
            enumerable: true,
            writable: false
        },
        appVersion: {
            value: navigator.appVersion.replace(/([^)]+)/, 'Windows NT 5.1'),
            configurable: false,
            enumerable: true,
            writable: false
        },
        platform: {
            value: 'Win32',
            configurable: false,
            enumerable: true,
            writable: false
        },
    });
} + ')();';

var s = document.createElement('script');
s.textContent = actualCode;
document.documentElement.appendChild(s);
s.remove();

manifest.json

{
    "name": "navigator.userAgent",
    "description": "Change navigator.userAgent to Windows on Chrome's download page.",
    "version": "1",
    "manifest_version": 2,
    "content_scripts": [{
        "run_at": "document_start",
        "js": ["contentscript.js"],
        "matches": [
            "*://www.google.com/intl/*/chrome/browser/*"
        ]
    }]
}

如您所见，我声明内容脚本而不是动态插入它，以确保我的代码在页面加载之前运行.此外，我正在使用其中一种技巧 在此答案中描述 以更改页面的 navigator 而不是隔离内容脚本世界中的其他一些 navigator.

As you can see, I'm declaring the content script instead of dynamically inserting it, to make sure that my code runs before the page is loaded. Further, I'm using one of the tricks described in this answer to change the page's navigator instead of some other navigator in the isolated content script world.

请注意，这只会修改从 JavaScript 中看到的 userAgent.如果要修改发送到服务器的用户代理，请查看 将自定义用户代理关联到特定的 Google Chrome 页面/标签.

Note that this only modifies the userAgent as seen from JavaScript. If you want to modify the user agent that's sent to the server, take a look at Associate a custom user agent to a specific Google Chrome page/tab.

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