electron-chrome-extensions

Chrome extension API support for Electron.

Electron provides basic support for Chrome extensions out of the box. However, it only supports a subset of APIs with a focus on DevTools. Concepts like tabs, popups, and extension actions aren't known to Electron.

This library aims to bring extension support in Electron up to the level you'd come to expect from a browser like Google Chrome. API behavior is customizable so you can define how to handle things like tab or window creation specific to your application's needs.

Install

npm install electron-chrome-extensions

Screenshots

uBlock Origin	Dark Reader

Usage

Basic

Simple browser using Electron's default session and one tab.

const { app, BrowserWindow } = require('electron')
const { ElectronChromeExtensions } = require('electron-chrome-extensions')

(async function main() {
  await app.whenReady()

  const extensions = new ElectronChromeExtensions()
  const browserWindow = new BrowserWindow()

  // Adds the active tab of the browser
  extensions.addTab(browserWindow.webContents, browserWindow)

  browserWindow.loadURL('https://samuelmaddock.com')
  browserWindow.show()
}())

Advanced

Multi-tab browser with full support for Chrome extension APIs.

For a complete example, see the electron-browser-shell project.

const { app, session, BrowserWindow } = require('electron')
const { ElectronChromeExtensions } = require('electron-chrome-extensions')

(async function main() {
  await app.whenReady()

  const browserSession = session.fromPartition('persist:custom')

  const extensions = new ElectronChromeExtensions({
    session: browserSession,
    createTab(details) {
      // Optionally implemented for chrome.tabs.create support
    },
    selectTab(tab, browserWindow) {
      // Optionally implemented for chrome.tabs.update support
    },
    removeTab(tab, browserWindow) {
      // Optionally implemented for chrome.tabs.remove support
    },
    createWindow(details) {
      // Optionally implemented for chrome.windows.create support
    }
  })

  const browserWindow = new BrowserWindow({
    webPreferences: {
      // Same session given to Extensions class
      session: browserSession,
      // Recommended options for loading remote content
      sandbox: true,
      contextIsolation: true
    }
  })

  // Adds the active tab of the browser
  extensions.addTab(browserWindow.webContents, browserWindow)

  browserWindow.loadURL('https://samuelmaddock.com')
  browserWindow.show()
}())

API

Class: ElectronChromeExtensions

Create main process handler for Chrome extension APIs.

`new ElectronChromeExtensions([options])`

options Object (optional)
- modulePath String (optional) - Path to electron-chrome-extensions module files. Might be needed if JavaScript bundlers like Webpack are used in your build process.
- session Electron.Session (optional) - Session which should support Chrome extension APIs. session.defaultSession is used by default.
- createTab(details) => Promise<[Electron.WebContents, Electron.BrowserWindow]> (optional) - Called when chrome.tabs.create is invoked by an extension. Allows the application to handle how tabs are created.
  - details chrome.tabs.CreateProperties
- selectTab(webContents, browserWindow) (optional) - Called when chrome.tabs.update is invoked by an extension with the option to set the active tab.
  - webContents Electron.WebContents - The tab to be activated.
  - browserWindow Electron.BrowserWindow - The window which owns the tab.
- removeTab(webContents, browserWindow) (optional) - Called when chrome.tabs.remove is invoked by an extension.
  - webContents Electron.WebContents - The tab to be removed.
  - browserWindow Electron.BrowserWindow - The window which owns the tab.
- createWindow(details) => Promise<Electron.BrowserWindow> (optional) - Called when chrome.windows.create is invoked by an extension.
  - details chrome.windows.CreateData
- removeWindow(browserWindow) => Promise<Electron.BrowserWindow> (optional) - Called when chrome.windows.remove is invoked by an extension.
  - browserWindow Electron.BrowserWindow

new ElectronChromeExtensions({
  createTab(details) {
    const tab = myTabApi.createTab()
    if (details.url) {
      tab.webContents.loadURL(details.url)
    }
    return [tab.webContents, tab.browserWindow]
  },
  createWindow(details) {
    const window = new BrowserWindow()
    return window
  }
})

For a complete usage example, see the browser implementation in the electron-browser-shell project.

Instance Methods

`extensions.addTab(tab, window)`

tab Electron.WebContents - A tab that the extension system should keep track of.
window Electron.BrowserWindow - The window which owns the tab.

Makes the tab accessible from the chrome.tabs API.

`extensions.selectTab(tab)`

tab Electron.WebContents

Notify the extension system that a tab has been selected as the active tab.

`extensions.getContextMenuItems(tab, params)`

tab Electron.WebContents - The tab from which the context-menu event originated.
params Electron.ContextMenuParams - Parameters from the context-menu event.

Returns Electron.MenuItem[] - An array of all extension context menu items given the context.

Instance Events

Event: 'browser-action-popup-created'

Returns:

popup PopupView - An instance of the popup.

Emitted when a popup is created by the chrome.browserAction API.

Element: `<browser-action-list>`

The <browser-action-list> element provides a row of browser actions which may be pressed to activate the chrome.browserAction.onClicked event or display the extension popup.

To enable the element on a webpage, you must define a preload script which injects the API on specific pages.

Attributes

partition string (optional) - The Electron.Session partition which extensions are loaded in. Defaults to the session in which <browser-action-list> lives.
tab string (optional) - The tab's Electron.WebContents ID to use for displaying the relevant browser action state. Defaults to the active tab of the current browser window.

Browser action example

Preload

Inject the browserAction API to make the <browser-action-list> element accessible in your application.

import { injectBrowserAction } from 'electron-chrome-extensions/dist/browser-action'

// Inject <browser-action-list> element into our page
if (location.href === 'webui://browser-chrome.html') {
  injectBrowserAction()
}

The use of import implies that your preload script must be compiled using a JavaScript bundler like Webpack.

Webpage

Add the <browser-action-list> element with attributes appropriate for your application.

<!-- Show actions for the same session and active tab of current window. -->
<browser-action-list></browser-action-list>

<!-- Show actions for custom session and active tab of current window. -->
<browser-action-list partition="persist:custom"></browser-action-list>

<!-- Show actions for custom session and a specific tab of current window. -->
<browser-action-list partition="persist:custom" tab="1"></browser-action-list>

Custom CSS

The <browser-action-list> element is a Web Component. Its styles are encapsulated within a Shadow DOM. However, it's still possible to customize its appearance using the CSS shadow parts selector ::part(name).

Accessible parts include action and badge.

/* Layout action buttons vertically. */
browser-action-list {
  flex-direction: column;
}

/* Modify size of action buttons. */
browser-action-list::part(action) {
  width: 16px;
  height: 16px;
}

/* Modify hover styles of action buttons. */
browser-action-list::part(action):hover {
  background-color: red;
  border-radius: 0;
}

Supported `chrome.*` APIs

The following APIs are supported, in addition to those already built-in to Electron.

Click to reveal supported APIs

`chrome.browserAction`

`chrome.commands`

chrome.commands.getAll
chrome.commands.onCommand

chrome.notifications.clear
chrome.notifications.create
chrome.notifications.getAll
chrome.notifications.getPermissionLevel
chrome.notifications.update
chrome.notifications.onButtonClicked
chrome.notifications.onClicked
chrome.notifications.onClosed

See Electron's Notification tutorial for how to support them in your app.

`chrome.runtime`

`chrome.storage`

chrome.storage.local
chrome.storage.managed - fallback to local
chrome.storage.sync - fallback to local

Limitations