function fn3( v )
{
console.log( 'fn3 ' + ( v || '' ) );
};
1 . 测试add & fire
var cb=new MyCallbacks();
cb.add(fn1)
cb.add(fn2)
cb.add(fn3)
cb.fire('hello')
输出：
fn1 hello
fn2 hello
fn3 hello
2.测试remove
var cb=new MyCallbacks();
cb.add(fn1)
cb.add(fn2)
cb.add(fn3)
cb.remove(fn1)
cb.fire('hello')
cb.remove(fn3)
cb.fire('hello')
输出：
fn1 hello
fn2 hello
fn3 hello
----------------------------
fn1 hello
fn2 hello
2.测试has
var cb=new MyCallbacks();
cb.add(fn1)
cb.add(fn2)
cb.add(fn3)
cb.has(fn1)
cb.has(fn3)
输出：
false
---------------
true
3.测试带参数的构造函数 : once
var cb=new MyCallbacks('once')
cb.add(fn1)
cb.fire('hello')
cb.fire('hello')
cb.add(fn2)
cb.fire('hello')
输出：
hello
-------------------
------------------
------------------------------
4.测试带参数的构造函数 : memory
var cb=new MyCallbacks('memory')
cb.add(fn1)
cb.fire('hello') // 输出 : fn1 hello
cb.add(fn2) // 输出 : fn2 hello
cb.fire('hello')
输出 :
fn1 hello
fn2 hello
5.测试带参数的构造函数 : stopOnFalse
var cb=new MyCallbacks('stopOnFalse')
cb.add(fn1)
cb.add(fn2)
cb.add(fn3)
cb.fire('hello')
输出：
fn1 hello
fn2 hello
6.测试带参数的构造函数 :unique
var cb=new MyCallbacks('unique')
b.add(fn3)
b.add(fn3)
cb.fire('hello')
输出：
fn3 hello
7. 测试带组合参数的构造函数：四个设置参数可以随意组合，一下只测试全部组合的情况， 不然要写16个测试用例 T_T
var cb=new MyCallbacks('once memory unique stopOnFalse')
cb.add(fn1) // 输出： fn1
cb.add(fn2) // 输出： fn2
cb.add(fn3) // 输出： fn3
cb.fire('hello')
输出：
fn1 hello
fn2 hello
cb.fire('hello') // 输出：没有输出
以下是官方API 文档：
Description: A multi-purpose callbacks list object that provides a powerful way to manage callback lists.The $.Callbacks() function is internally used to provide the base functionality behind the jQuery $.ajax() and$.Deferred() components. It can be used as a similar base to define functionality for new components.
构造函数 ： jQuery.Callbacks( flags )
flags
Type: String
An optional list of space-separated flags that change how the callback list behaves.
Possible flags:
once: Ensures the callback list can only be fired once (like a Deferred).
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)
复制代码 代码如下:
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
复制代码 代码如下: