jquery1.83 之前所有与异步列队相关的模块详细介绍(4)

(function( jQuery ) {
var topics = {},
sliceTopic = [].slice;
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;
};
jQuery.extend({
subscribe: function( id ) {
var topic = jQuery.Topic( id ),
args = sliceTopic.call( arguments, 1 );
topic.subscribe.apply( topic, args );
return {
topic: topic,
args: args
};
},
unsubscribe: function( id ) {
var topic = id && id.topic || jQuery.Topic( id );
topic.unsubscribe.apply( topic, id && id.args ||
sliceTopic.call( arguments, 1 ) );
},
publish: function( id ) {
var topic = jQuery.Topic( id );
topic.publish.apply( topic, sliceTopic.call( arguments, 1 ) );
}
});
})( jQuery );

虽然把大量代码移动callbacks，但1.7的Deferred却一点没有没变小，它变得更重型，它由三个函数列队组成了。并且返回的是Promise对象，比原来多出了pipe, state, progress, always方法。ajax那边就变成这样：

复制代码 代码如下: