content/loader
The loader
module provides one of the building blocks for those modules
in the SDK that use
content scripts to interact with web content,
such as the panel
and page-mod
modules.
The module exports a constructor for the Loader
object, which is composed
from the EventEmitter trait, so it
inherits on()
, once()
, and removeListener()
functions that
enable its users to listen to events.
Loader
adds code to initialize and validate a set of properties for
managing content scripts:
contentURL
contentScript
contentScriptFile
contentScriptWhen
contentScriptOptions
allow
When certain of these properties are set, the Loader
emits a
propertyChange
event, enabling its users to take the appropriate action.
The Loader
is used by modules that use content scripts but don't
themselves load content, such as page-mod
.
Modules that load their own content, such as
panel
, page-worker
, and
widget
, use the
symbiont
module instead.
Symbiont
inherits from Loader
but contains its own frame into which
it loads content supplied as the contentURL
option.
Example:
The following code creates a wrapper on a hidden frame that reloads a web page
in the frame every time the contentURL
property is changed:
var hiddenFrames = require("sdk/frame/hidden-frame");
var { Loader } = require("sdk/content/content");
var PageLoader = Loader.compose({
constructor: function PageLoader(options) {
options = options || {};
if (options.contentURL)
this.contentURL = options.contentURL;
this.on('propertyChange', this._onChange = this._onChange.bind(this));
let self = this;
hiddenFrames.add(hiddenFrames.HiddenFrame({
onReady: function onReady() {
let frame = self._frame = this.element;
self._emit('propertyChange', { contentURL: self.contentURL });
}
}));
},
_onChange: function _onChange(e) {
if ('contentURL' in e)
this._frame.setAttribute('src', this._contentURL);
}
});
API Reference
Classes
Loader
Properties
contentScriptFile : array
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 : array
The texts of content scripts to load. Content scripts specified by this
property are loaded after those specified by the contentScriptFile
property.
contentScriptWhen : string
When to load the content scripts. This may take 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 : object
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 : string
The URL of the content loaded.
allow : object
Permissions for the content, with the following keys: