memory: Keeps track of previous values and will call any callback added after the list has been fired right away with the latest “memorized” values (like a Deferred).
unique: Ensures a callback can only be added once (so there are no duplicates in the list).
stopOnFalse: Interrupts callings when a callback returns false.
By default a callback list will act like an event callback list and can be “fired” multiple times.
Two specific methods were being used above: .add() and .fire(). The .add() method supports adding new callbacks to the callback list, while the .fire() method executes the added functions and provides a way to pass arguments to be processed by the callbacks in the same list.
利用Callbacks 实现发布订阅模式 pub/sub: (官方文档)
var topics = {};
jQuery.Topic = function ( id )
{
var callbacks,
method,
topic = id && topics[id];
if ( !topic )
{
callbacks = jQuery.Callbacks();
topic = {
publish: callbacks.fire,
subscribe: callbacks.add,
unsubscribe: callbacks.remove
};
if ( id )
{
topics[id] = topic;
}
}
return topic;
};
使用
$.Topic( ‘mailArrived’ ).subscribe( function ( e )
{
console.log( ‘Your have new email! ‘ );
