WebExtension JavaScript API 可以在附加组件的后台脚本和附加组件定义的任何浏览器动作页面动作中使用。这里的部分API也可以通过附加组件的内容脚本访问(见内容脚本指南列表)。

要使用更强大的 API,您需要在您的 manifest.json 中申请权限

您可以使用 browser 命名空间访问这些 API。

function logTabs(tabs) {

browser.tabs.query({currentWindow: true}, logTabs);

许多 API 为异步,返回一个 Promise

function logCookie(c) {

function logError(e) {

var setCookie = browser.cookies.set(
  {url: "https://developer.mozilla.org/"}
setCookie.then(logCookie, logError);

请注意,这不同于 Google Chrome 的扩展系统,它使用 chrome 而非 browser 名字空间,并且对异步函数使用回调而不是 promises。为辅助移植,Firefox 实现的 WebExtensions 支持 chrome 和回调以及 browser 和 promises。Mozilla 也写了一个 polyfill 使使用 browser 和 promises 的代码能不经修改的在 Chrome 中使用:https://github.com/mozilla/webextension-polyfill

微软 Edge 使用 browser 名字空间,但尚不支持基于 promise 的异步API。目前在 Edge 中,异步 API 必须使用回调。

并非所有浏览器都支持这里的所有 API:详情见浏览器对 JavaScript API 的支持


Schedule code to run at a specific time in the future. This is like setTimeout() and setInterval(), except that those functions don't work with background pages that are loaded on demand.

API reference documentation


The WebExtensions bookmarks API lets an add-on interact with and manipulate the browser's bookmarking system. You can use it to bookmark pages, retrieve existing bookmarks, and edit, remove, and organize bookmarks.

API reference documentation


Adds a button to the browser's toolbar.

API reference documentation


Enables WebExtensions to clear data that is accumulated while the user is browsing.

API reference documentation


Listen for the user executing commands that you have registered using the commands manifest.json key.

API reference documentation


Add items to the browser's context menu, to be displayed in the contexts you specify. For example, you can show the item only when the user clicks on an image, or on an editable element, or when part of a page is selected.

API reference documentation


Work with contextual identities: list, create, remove, and update contextual identities.

API reference documentation


Enables WebExtensions to get and set cookies, and be notified when they change.

API reference documentation


Enables WebExtensions to interact with the browser's download manager. You can use this API module to download files, cancel, pause, resume downloads, and show downloaded files in the file manager.

API reference documentation


Common types used by APIs that dispatch events.

API reference documentation


Utilities related to your add-on. Get URLs to resources packages with your add-on, get the Window object for your add-on's pages, get the values for various settings. Note that the messaging APIs in this module are deprecated in favor of the equivalent APIs in the runtime module.

API reference documentation


Some common types used in other WebExtension APIs.

API reference documentation


Use the history API to interact with the browser history.

API reference documentation


Functions to internationalize your add-on. You can use these APIs to get localized strings from locale files packaged with your add-on, find out the browser's current language, and find out the value of its Accept-Language header.

API reference documentation


Use the identity API to get an OAuth2 authorization code or access token, which an add-on can then use to access user data from a service which supports OAuth2 access (such as a Google or a Facebook account).

API reference documentation


Find out when the user's system is idle, locked, or active.

API reference documentation


Get information about installed add-ons.

API reference documentation


Display notifications to the user, using the underlying operating system's notification mechanism. Because this API uses the operating system's notification mechanism, the details of how notifications appear and behave may differ according to the operating system and the user's settings.

API reference documentation


Enables WebExtensions to implement customised behavior when the user types into the browser's address bar.

API reference documentation


A page action is a clickable icon inside the browser's address bar.

API reference documentation


This module provides information about your add-on and the environment it's running in.

API reference documentation


Use the sessions API to list, and restore, tabs and windows that have been closed while the browser has been running.

API reference documentation


Enables WebExtensions to store and retrieve data, and listen for changes to stored items.

API reference documentation


Interact with the browser's tab system.

API reference documentation


Use the topSites API to get an array containing all the sites listed in the browser's "New Tab" page.

API reference documentation


Add event listeners for the various stages of a navigation. A navigation consists of a frame in the browser transitioning from one URL to another, usually (but not always) in response to a user action like clicking a link or entering a URL in the location bar.

API reference documentation


Add event listeners for the various stages of making an HTTP request. The event listener receives detailed information about the request, and can modify or cancel the request.

API reference documentation


Interact with browser windows. You can use this API to get information about open windows and to open, modify, and close windows. You can also listen for window open, close, and activate events.

API reference documentation


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