Add-ons using the techniques described in this document are considered a legacy technology in Firefox. Don't use these techniques to develop new add-ons. Use WebExtensions instead. If you maintain an add-on which uses the techniques described here, consider migrating it to use WebExtensions.
From Firefox 53 onwards, no new legacy add-ons will be accepted on addons.mozilla.org (AMO).
From Firefox 57 onwards, WebExtensions will be the only supported extension type, and Firefox will not load other types.
Even before Firefox 57, changes coming up in the Firefox platform will break many legacy extensions. These changes include multiprocess Firefox (e10s), sandboxing, and multiple content processes. Legacy extensions that are affected by these changes should migrate to WebExtensions if they can. See the "Compatibility Milestones" document for more.
A wiki page containing resources, migration paths, office hours, and more, is available to help developers transition to the new technologies.
Unstable
Used by SDK modules that can load web content and attach content scripts to it.
Usage
A Symbiont
loads the specified contentURL
and content scripts into a frame, and sets up an asynchronous channel between the content scripts and the add-on code, enabling them to exchange messages using the port
or postMessage
APIs. You map optionally pass a frame into the Symbiont
's constructor: if you don't, then a new hidden frame will be created to host the content.
This trait is composed from the Loader
and Worker
traits. It inherits functions to load and configure content scripts from the Loader
, and functions to exchange messages between content scripts and the main add-on code from the Worker
.
var { Symbiont } = require('sdk/content/content'); var Thing = Symbiont.resolve({ constructor: '_init' }).compose({ constructor: function Thing(options) { // `getMyFrame` returns the host application frame in which // the page is loaded. this._frame = getMyFrame(); this._init(options) } });
See the panel module for a real-world example of usage of this module.
Globals
Constructors
Symbiont(options)
Creates a content symbiont.
Parameters
options : object
Optional options:
Name | Type | |
---|---|---|
frame | object |
The host application frame in which the page is loaded. If frame is not provided hidden one will be created. |
contentScriptWhen | string |
When to load the content scripts. This may take one of the following values:
This property is optional and defaults to "end". |
contentScriptOptions | object |
Read-only value exposed to content scripts under Any kind of jsonable value (object, array, string, etc.) can be used here. Optional. |
allow | object |
Permissions for the content, with the following keys: |
script | boolean |
Whether or not to execute script in the content. Defaults to true. Optional. Optional. |
Symbiont
Symbiont is composed from the Worker trait, therefore instances of Symbiont and their descendants expose all the public properties exposed by Worker along with additional public properties that are listed below:
Properties
contentScriptFile
The local file URLs of content scripts to load. Content scripts specified by this property are loaded before those specified by the contentScript
property.
contentScript
The texts of content scripts to load. Content scripts specified by this property are loaded after those specified by the contentScriptFile
property.
contentScriptWhen
When to load the content scripts. This may have one of the following values:
- "start": load content scripts immediately after the document element for the page is inserted into the DOM, but before the DOM content itself has been loaded
- "ready": load content scripts once DOM content has been loaded, corresponding to the DOMContentLoaded event
- "end": load content scripts once all the content (DOM, JS, CSS, images) for the page has been loaded, at the time the window.onload event fires
contentScriptOptions
Read-only value exposed to content scripts under self.options
property.
Any kind of jsonable value (object, array, string, etc.) can be used here. Optional.
contentURL
The URL of the content loaded.
allow
Permissions for the content, with a single boolean key called script
which defaults to true and indicates whether or not to execute scripts in the content.