如何覆盖 JavaScript web api 通知对象

2022-01-10 00:00:00 electron javascript

我有一个场景，我需要为电子窗口内的 web 视图中加载的网页打开和关闭通知.为此，我在 webview 中注入了一个 preload 文件，它像这样覆盖 Notification 对象.

I have a scenario where I need to toggle notifications on and off for a webpage that is loaded in a webview inside an electron window. To do that I have injected a preload file inside the webview that overrides the Notification object like this. 

window.oldNotification = window.Notification;
window.Notification = function() {
    let notificationEnabled = localStorage.getItem('notification-permissions') === 'true';
    if (notificationEnabled) {
        new window.oldNotification(...arguments);
    }
};

我正在通过更改本地存储变量来启用和禁用通知.

I am enabling and disabling notifications by changing a local storage variable.

问题是我要控制的网页正在使用 Notification.permission 方法 (参考这里).现在我的新通知对象上没有权限属性.我无法以可以更新其构造函数的方式覆盖 Notification 对象，以便我可以禁用通知并拥有原始 Notification 对象的其他属性.

The issue is that the webpage that I want to control is using Notification.permission method (refer this). Now my new Notification object has no permission property on it. I am not able to override the Notification object in a way where I can update its constructor so that I can disable the notification and also have other properties of the original Notification object.

有没有办法实现这一点，或者这根本不可能?绝对欢迎任何帮助或建议.

Is there a way to achieve this or is this not possible at all? Any help or suggestion is absolutely welcome.

推荐答案

您可以轻松模拟 Notification API

You can easily emulate Notification API

window.Notification = function() {
  const notificationEnabled = Notification.permission === 'granted';
  return notificationEnabled ? new window.oldNotification(...arguments) : {};
};

Object.defineProperty(Notification, 'permission', {
  get() {
    return localStorage.getItem('notification-permissions') === 'true' ? 'granted' : 'denied';
  }
});

Notification.requestPermission = (callback) => {
  if (typeof callback === 'function') {
    callback(Notification.permission);
  }

  return Promise.resolve(Notification.permission);
};

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