自己动手实现jQuery Callbacks完整功能代码详解

用法和$.Callbacks完全一致 , 但是只是实现了add , remove , fire , empty, has和带参数的构造函数功能,  $.Callbacks 还有disable,disabled, fireWith , fired , lock, locked 方法

代码如下:

代码如下:

String.prototype.trim = function ()
        {
            return this.replace( /^\s+|\s+$/g, '' );
        };

// Simulate jQuery.Callbacks object
        function MyCallbacks( options )
        {
            var ops = { once: false, memory: false, unique: false, stopOnFalse: false };

if ( typeof options === 'string' && options.trim() !== '' )
            {
                var opsArray = options.split( /\s+/ );
                for ( var i = 0; i < options.length; i++ )
                {
                    if ( opsArray[i] === 'once' )
                        ops.once = true;
                    else if ( opsArray[i] === 'memory' )
                        ops.memory = true;
                    else if ( opsArray[i] === 'unique' )
                        ops.unique = true;
                    else if ( opsArray[i] === 'stopOnFalse' )
                        ops.stopOnFalse = true;
                }
            }

var ar = [];
            var lastArgs = null;
            var firedTimes = 0;

function hasName( name )
            {
                var h = false;

if ( typeof name === 'string'
                    && name !== null
                    && name.trim() !== ''
                    && ar.length > 0 )
                {
                    for ( var i = 0; i < ar.length; i++ )
                    {
                        if ( ar[i].name === name )
                        {
                            h = true;
                            break;
                        }
                    }
                }

return h;
            }

// add a function
            this.add = function ( fn )
            {
                if ( typeof fn === 'function' )
                {
                    if ( ops.unique )
                    {
                        // check whether it had been added before
                        if ( fn.name !== '' && hasName( fn.name ) )
                        {
                            return this;
                        }
                    }

ar.push( fn );

if ( ops.memory )
                    {
                        // after added , call it immediately
                        fn.call( this, lastArgs );
                    }
                }

return this;
            };

// remove a function
            this.remove = function ( fn )
            {
                if ( typeof ( fn ) === 'function'
                    && fn.name !== ''
                    && ar.length > 0 )
                {
                    for ( var i = 0; i < ar.length; i++ )
                    {
                        if ( ar[i].name === fn.name )
                        {
                            ar.splice( i, 1 );
                        }
                    }
                }

return this;
            };

// remove all functions
            this.empty = function ()
            {
                ar.length = 0;
                return this;
            };

// check whether it includes a specific function
            this.has = function ( fn )
            {
                var f = false;

if ( typeof ( fn ) === 'function'
                    && fn.name !== ''
                    && ar.length > 0 )
                {
                    for ( var i = 0; i < ar.length; i++ )
                    {
                        if ( ar[i].name === fn.name )
                        {
                            f = true;
                            break;
                        }
                    }
                }

return f;
            };

// invoke funtions it includes one by one
            this.fire = function ( args )
            {
                if ( ops.once && firedTimes > 0 )
                {
                    return this;
                }

if ( ar.length > 0 )
                {
                    var r;

for ( var i = 0; i < ar.length; i++ )
                    {
                        r = ar[i].call( this, args );

if ( ops.stopOnFalse && r === false )
                        {
                            break;
                        }
                    }
                }

firedTimes++;

if ( ops.memory )
                {
                    lastArgs = args;
                }

return this;
            };
        };

测试函数如下:(注意fn1 fn2是匿名函数, fn2返回false , fn3是有“名”函数)

代码如下:

var fn1 = function ( v )
        {
            console.log( 'fn1 ' + ( v || '' ) );
        };

var fn2 = function ( v )
        {
            console.log( 'fn2 ' + ( v || '' ) );
            return false;
        };

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)

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

代码如下:

$.Topic( 'mailArrived' ).subscribe( function ( e )
        {
            console.log( 'Your have new email! ' );
            console.log( "mail title : " + e.title );
            console.log( "mail content : " + e.content );
        }
        );

$.Topic( 'mailArrived' ).publish( { title: 'mail title', content: 'mail content' } );

实现了其余的全部功能 :callbacks.disable , callbacks.disabled,   callbacks.fired,callbacks.fireWith, callbacks.lock, callbacks.locked ,然后重构了下代码结构, 将实现放入了匿名函数内, 然后通过工厂方法 window.callbacks 返回实例,以免每次使用必须 new .

具体代码如下, 有兴趣和时间的可以对照jQuery版本的Callbacks对比下 :

代码如下:

( function ( window, undefined )
        {
            // Simulate jQuery.Callbacks object
            function Callbacks( options )
            {
                var ops = { once: false, memory: false, unique: false, stopOnFalse: false },
                    ar = [],
                    lastArgs = null,
                    firedTimes = 0,
                    _disabled = false,
                    _locked = false;

if ( typeof options === 'string' && options.trim() !== '' )
                {
                    var opsArray = options.split( /\s+/ );
                    for ( var i = 0; i < options.length; i++ )
                    {
                        if ( opsArray[i] === 'once' )
                            ops.once = true;
                        else if ( opsArray[i] === 'memory' )
                            ops.memory = true;
                        else if ( opsArray[i] === 'unique' )
                            ops.unique = true;
                        else if ( opsArray[i] === 'stopOnFalse' )
                            ops.stopOnFalse = true;
                    }
                }

function hasName( name )
                {
                    var h = false;

if ( typeof name === 'string'
                        && name !== null
                        && name.trim() !== ''
                        && ar.length > 0 )
                    {
                        for ( var i = 0; i < ar.length; i++ )
                        {
                            if ( ar[i].name === name )
                            {
                                h = true;
                                break;
                            }
                        }
                    }

return h;
                }

// add a function
                this.add = function ( fn )
                {
                    if ( typeof fn === 'function' )
                    {
                        if ( ops.unique )
                        {
                            // check whether it had been added before
                            if ( fn.name !== '' && hasName( fn.name ) )
                            {
                                return this;
                            }
                        }

ar.push( fn );

if ( ops.memory )
                        {
                            // after added , call it immediately
                            fn.call( this, lastArgs );
                        }
                    }

return this;
                };

// remove a function
                this.remove = function ( fn )
                {
                    if ( typeof ( fn ) === 'function'
                        && fn.name !== ''
                        && ar.length > 0 )
                    {
                        for ( var i = 0; i < ar.length; i++ )
                        {
                            if ( ar[i].name === fn.name )
                            {
                                ar.splice( i, 1 );
                            }
                        }
                    }

return this;
                };

// remove all functions
                this.empty = function ()
                {
                    ar.length = 0;
                    return this;
                };

// check whether it includes a specific function
                this.has = function ( fn )
                {
                    var f = false;

if ( typeof ( fn ) === 'function'
                        && fn.name !== ''
                        && ar.length > 0 )
                    {
                        for ( var i = 0; i < ar.length; i++ )
                        {
                            if ( ar[i].name === fn.name )
                            {
                                f = true;
                                break;
                            }
                        }
                    }

return f;
                };

this.disable = function ()
                {
                    _disabled = true;
                    return this;
                };

this.disabled = function ()
                {
                    return _disabled;
                };

this.fired = function ()
                {
                    return firedTimes > 0;
                };

function _fire( context, args )
                {
                    if ( _disabled || ops.once && firedTimes > 0 || _locked )
                    {
                        return;
                    }

if ( ar.length > 0 )
                    {
                        var r;

for ( var i = 0; i < ar.length; i++ )
                        {
                            r = ar[i].call( context, args );

if ( ops.stopOnFalse && r === false )
                            {
                                break;
                            }
                        }
                    }

firedTimes++;

if ( ops.memory )
                    {
                        lastArgs = args;
                    }

};

this.fireWith = function ( context, args )
                {
                    context = context || this;
                    _fire( context, args );
                    return this;
                };

this.fire = function ( args )
                {
                    _fire( this, args );
                    return this;
                };

this.lock = function ()
                {
                    _locked = true;
                    return this;
                };

this.locked = function ()
                {
                    return _locked;
                };

};

// exposed to global as a factory method
            window.callbacks = function ( options )
            {
                return new Callbacks( options );
            };

} )( window );

(0)

相关推荐

  • jQuery AJAX回调函数this指向问题

    如在全局作用域调用一个含this的对象,此时当前对象的this指向的是window.为了让this的指向符合自己的意愿,JavaScript提供了两个方法用以改变this的指向,它们是call和apply,当然也有利用闭包来实现的方法.本文通过一个例子来说明这些问题. 先看一段演示代码,这代码只供演示用,没有实际意义. 复制代码 代码如下: //一个没有实际意义的socket连接对象 var socket = { connect: function(host, port) { alert('Co

  • jQuery Tips 为AJAX回调函数传递额外参数的方法

    具体到这个例子,我们希望button1和button2点击之后,用AJAX的方式取example.html的内容,然后动态更新页面的id=callbackdemo3的div HTML如下: 复制代码 代码如下: <div id="callbackdemo1"> <button id="button1">ajax load1</button><br/> </div> <div id="call

  • jquery.Callbacks的实现详解

    前言 jQuery.Callbacks是jquery在1.7版本之后加入的,是从1.6版中的_Deferred对象中抽离的,主要用来进行函数队列的add.remove.fire.lock等操作,并提供once.memory.unique.stopOnFalse四个option进行一些特殊的控制. 功能介绍 jq的Callbacks模块主要是为其他模块提供服务的,他就像一个温柔的小女人,在背后默默地付出.Deferred就像一个巨人,在jq中那么的突出,但在内部,他受到Callbacks的服务.

  • jQuery源码分析之Callbacks详解

    代码的本质突出顺序.有序这一概念,尤其在javascript--毕竟javascript是单线程引擎. javascript拥有函数式编程的特性,而又因为javascript单线程引擎,我们的函数总是需要有序的执行.优秀代码常常 把函数切割成各自的模块,然后在某一特定条件下执行,既然这些函数是有序的执行,那么我们为什么不编写一个统一管理的对象,来帮助我们管理这些函数--于是,Callbacks(回调函数)诞生. 什么是Callbacks javascript中充斥着函数编程,例如最简单的wind

  • Jquery版本导致Ajax不执行success回调函数

    对于使用ajax来请求数据已经不是第一次使用(一直觉得也就那么回事),就在昨天居然遇到了一个问题?项目中需要用到ajax来进行数据的请求,于是三下五除二的将ajax代码拷贝到项目中,前端,后台数据处理完毕,测试(心想可以休息下下了),谁知数据成功返回.前端没报错,后台也没错,硬是没有执行success回调函数,心凉了一半. 接下来就是找原因,查看原先代码,百度,json格式检查,终于发现问题所在 罪魁祸首居然是Jquery版本所引起的. Jquery版本:jquery-1.9.0.min.js

  • 使用jQuery中的when实现多个AJAX请求对应单个回调的例子分享

    我知道这些函数都是异步执行(asyncronously)并且会延迟一段时间返回,所以我想知道是否有一种方式,使我可以使用单个回调,并行地加载它们,就像JS加载器 curljs 所做的那样. 很幸运! 通过jQuery.when, 我可以并发地加载两个请求,只执行一次回调! jQuery 脚本正如我提到的,下面是加载脚本和一个JSON资源的用例: 复制代码 代码如下: $.when( $.getScript('/media/js/wiki-min.js?build=21eb633'),  $.ge

  • jQuery.Callbacks()回调函数队列用法详解

    本文实例讲述了jQuery.Callbacks()回调函数队列用法.分享给大家供大家参考,具体如下: 1.jQuery.Callbacks The jQuery.Callbacks() function, introduced in version 1.7, returns a multi-purpose object that provides a powerful way to manage callback lists. It supports adding, removing, firi

  • 从零学jquery之如何使用回调函数

    在类C语言中通常通过函数指针/引用的方式传递. jquery也提供类似的回调函数机制.但是如何正确传递回调函数仍然值得一提.  1.不带参数的回调 复制代码 代码如下: $.get('myhtmlpage.html', myCallBack); 其中myCallBack是函数名字.函数是javascript的基础.可以当作引用变量一样传递. 2.带参数的回调 很自然的,按照以往的经验,我们会认为带参数的回调是下面的样子: 复制代码 代码如下: $.get('myhtmlpage.html', m

  • Jquery Post处理后不进入回调的原因及解决方法

    今天做一个简单的增加数据,通过Jquery的Post方法,把Json数据传到Jsp后台,处理后却怎么都不进入回调函数, $.post("addGs.do","x=" + JSON.stringify(x) ,function(d){ alert('成功'); } ,"json" ); 通过FF调试发现返回数据正常,200Ok, 没办法,又看看Jquery API,说如果最后的参数是Json时,要求返回的数据是Json格式, 会不会是返回的Json

  • jQuery回调函数的定义及用法实例

    本文实例讲述了jQuery回调函数的定义及用法.分享给大家供大家参考.具体分析如下: jQuery代码中对回调函数有着广泛的应用,对其有精准的理解是非常有必要的,下面就通过实例对此方法进行简单的介绍. 代码实例如下: 利用回调函数,当div全部隐藏之后弹出一个提示框. 复制代码 代码如下: <!DOCTYPE html> <html> <head> <meta charset=" utf-8"> <meta name="a

随机推荐