docs: no class inheritance (#47432)

Co-authored-by: trop[bot] <37223003+trop[bot]@users.noreply.github.com>
Co-authored-by: Erick Zhao <ezhao@slack-corp.com>

docs/api/base-window.md

@@ -99,6 +99,10 @@ Process: [Main](../glossary.md#main-process)
 
 It creates a new `BaseWindow` with native properties as set by the `options`.
 
+> [!WARNING]
+> Electron's built-in classes cannot be subclassed in user code.
+> For more information, see [the FAQ](../faq.md#class-inheritance-does-not-work-with-electron-built-in-modules).
+
 ### `new BaseWindow([options])`
 
 * `options` [BaseWindowConstructorOptions](structures/base-window-options.md?inline) (optional)

docs/api/browser-view.md

@@ -38,6 +38,10 @@ Process: [Main](../glossary.md#main-process)
 This module cannot be used until the `ready` event of the `app`
 module is emitted.
 
+> [!WARNING]
+> Electron's built-in classes cannot be subclassed in user code.
+> For more information, see [the FAQ](../faq.md#class-inheritance-does-not-work-with-electron-built-in-modules).
+
 ### Example
 
 ```js

docs/api/browser-window.md

@@ -150,6 +150,10 @@ Process: [Main](../glossary.md#main-process)
 
 It creates a new `BrowserWindow` with native properties as set by the `options`.
 
+> [!WARNING]
+> Electron's built-in classes cannot be subclassed in user code.
+> For more information, see [the FAQ](../faq.md#class-inheritance-does-not-work-with-electron-built-in-modules).
+
 ### `new BrowserWindow([options])`
 
 * `options` [BrowserWindowConstructorOptions](structures/browser-window-options.md?inline) (optional)

docs/api/image-view.md

@@ -42,6 +42,10 @@ Process: [Main](../glossary.md#main-process)
 
 `ImageView` is an [EventEmitter][event-emitter].
 
+> [!WARNING]
+> Electron's built-in classes cannot be subclassed in user code.
+> For more information, see [the FAQ](../faq.md#class-inheritance-does-not-work-with-electron-built-in-modules).
+
 ### `new ImageView()` _Experimental_
 
 Creates an ImageView.

docs/api/ipc-main-service-worker.md

@@ -11,6 +11,10 @@ Process: [Main](../glossary.md#main-process)
 
 <!-- TODO(samuelmaddock): refactor doc gen to allow generics to reduce duplication -->
 
+> [!WARNING]
+> Electron's built-in classes cannot be subclassed in user code.
+> For more information, see [the FAQ](../faq.md#class-inheritance-does-not-work-with-electron-built-in-modules).
+
 ### Instance Methods
 
 #### `ipcMainServiceWorker.on(channel, listener)`

docs/api/menu-item.md

@@ -6,6 +6,10 @@ Process: [Main](../glossary.md#main-process)
 
 See [`Menu`](menu.md) for examples.
 
+> [!WARNING]
+> Electron's built-in classes cannot be subclassed in user code.
+> For more information, see [the FAQ](../faq.md#class-inheritance-does-not-work-with-electron-built-in-modules).
+
 ### `new MenuItem(options)`
 
 * `options` Object

docs/api/menu.md

@@ -6,6 +6,10 @@
 
 Process: [Main](../glossary.md#main-process)
 
+> [!WARNING]
+> Electron's built-in classes cannot be subclassed in user code.
+> For more information, see [the FAQ](../faq.md#class-inheritance-does-not-work-with-electron-built-in-modules).
+
 ### `new Menu()`
 
 Creates a new menu.

docs/api/message-channel-main.md

@@ -33,6 +33,10 @@ ipcRenderer.on('port', (e) => {
 })
 ```
 
+> [!WARNING]
+> Electron's built-in classes cannot be subclassed in user code.
+> For more information, see [the FAQ](../faq.md#class-inheritance-does-not-work-with-electron-built-in-modules).
+
 ### Instance Properties
 
 #### `channel.port1`

docs/api/notification.md

@@ -4,12 +4,9 @@
 
 Process: [Main](../glossary.md#main-process)
 
-:::info Renderer process notifications
-
-If you want to show notifications from a renderer process you should use the
-[web Notifications API](../tutorial/notifications.md)
-
-:::
+> [!NOTE]
+> If you want to show notifications from a renderer process you should use the
+> [web Notifications API](../tutorial/notifications.md)
 
 ## Class: Notification
 
@@ -21,6 +18,10 @@ Process: [Main](../glossary.md#main-process)
 
 It creates a new `Notification` with native properties as set by the `options`.
 
+> [!WARNING]
+> Electron's built-in classes cannot be subclassed in user code.
+> For more information, see [the FAQ](../faq.md#class-inheritance-does-not-work-with-electron-built-in-modules).
+
 ### Static Methods
 
 The `Notification` class has the following static methods:

docs/api/share-menu.md

@@ -13,6 +13,10 @@ For including the share menu as a submenu of other menus, please use the
 
 Process: [Main](../glossary.md#main-process)
 
+> [!WARNING]
+> Electron's built-in classes cannot be subclassed in user code.
+> For more information, see [the FAQ](../faq.md#class-inheritance-does-not-work-with-electron-built-in-modules).
+
 ### `new ShareMenu(sharingItem)`
 
 * `sharingItem` SharingItem - The item to share.

docs/api/touch-bar.md

@@ -1,5 +1,9 @@
 # TouchBar
 
+> [!WARNING]
+> Electron's built-in classes cannot be subclassed in user code.
+> For more information, see [the FAQ](../faq.md#class-inheritance-does-not-work-with-electron-built-in-modules).
+
 ## Class: TouchBar
 
 > Create TouchBar layouts for native macOS applications

docs/api/tray.md

@@ -25,6 +25,10 @@ app.whenReady().then(() => {
 })
 ```
 
+> [!WARNING]
+> Electron's built-in classes cannot be subclassed in user code.
+> For more information, see [the FAQ](../faq.md#class-inheritance-does-not-work-with-electron-built-in-modules).
+
 **Platform Considerations**
 
 **Linux**

docs/api/view.md

@@ -25,6 +25,10 @@ Process: [Main](../glossary.md#main-process)
 
 `View` is an [EventEmitter][event-emitter].
 
+> [!WARNING]
+> Electron's built-in classes cannot be subclassed in user code.
+> For more information, see [the FAQ](../faq.md#class-inheritance-does-not-work-with-electron-built-in-modules).
+
 ### `new View()`
 
 Creates a new `View`.

docs/api/web-contents-view.md

@@ -32,6 +32,10 @@ Process: [Main](../glossary.md#main-process)
 
 `WebContentsView` is an [EventEmitter][event-emitter].
 
+> [!WARNING]
+> Electron's built-in classes cannot be subclassed in user code.
+> For more information, see [the FAQ](../faq.md#class-inheritance-does-not-work-with-electron-built-in-modules).
+
 ### `new WebContentsView([options])`
 
 * `options` Object (optional)

docs/faq.md

@@ -152,6 +152,14 @@ The effect is visible only on (some?) LCD screens. Even if you don't see a diffe
 
 Notice that just setting the background in the CSS does not have the desired effect.
 
+## Class inheritance does not work with Electron built-in modules
+
+Electron classes cannot be subclassed with the [`extends`](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Classes/extends)
+keyword (also known as class inheritance). This feature was never implemented in Electron due
+to the added complexity it would add to C++/JavaScript interop in Electron's internals.
+
+For more information, see [electron/electron#23](https://github.com/electron/electron/issues/23).
+
 [memory-management]: https://developer.mozilla.org/en-US/docs/Web/JavaScript/Memory_Management
 [closures]: https://developer.mozilla.org/en-US/docs/Web/JavaScript/Closures
 [storage]: https://developer.mozilla.org/en-US/docs/Web/API/Storage