1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
|
<!-- contributed by Atul Varma [atul@mozilla.com] -->
<!-- edited by Noelle Murata [fiveinchpixie@gmail.com] -->
The `observer-service` module provides access to the
application-wide observer service singleton.
For a list of common observer topics across a variety of Mozilla-based
applications, see the MDC page on
[Observer Notifications](https://developer.mozilla.org/en/Observer_Notifications).
## Observer Callbacks ##
Observer callbacks are functions of the following form:
function callback(subject, data) {
/* Respond to the event notification here... */
}
In the above example, `subject` is any JavaScript object, as is
`data`. The particulars of what the two contain are specific
to the notification topic.
<api name="add">
@function
Adds an observer callback to be triggered whenever a notification matching the
topic is broadcast throughout the application.
@param topic {string}
The topic to observe.
@param callback {function,object}
Either a function or an object that implements [`nsIObserver`](http://mxr.mozilla.org/mozilla-central/source/xpcom/ds/nsIObserver.idl).
If a function, then it is called when the notification occurs. If an object,
then its `observe()` method is called when the notification occurs.
@param [thisObject] {object}
An optional object to use as `this` when a function callback is called.
</api>
<api name="remove">
@function
Unsubscribes a callback from being triggered whenever a notification
matching the topic is broadcast throughout the application.
@param topic {string}
The topic being observed by the previous call to `add()`.
@param callback {function,object}
The callback subscribed in the previous call to `add()`, either a function or
object.
@param [thisObject] {object}
If `thisObject` was passed to the previous call to `add()`, it should be
passed to `remove()` as well.
</api>
<api name="notify">
@function
Broadcasts a notification event for a topic, passing a subject and data to all
applicable observers in the application.
@param topic {string}
The topic about which to broadcast a notification.
@param [subject] {value}
Optional information about the topic. This can be any JS object or primitive.
If you have multiple values to pass to observers, wrap them in an object,
e.g., `{ foo: 1, bar: "some string", baz: myObject }`.
</api>
|
