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' )
           &nbsnbsp;    {
                    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 !== ''
    nbsp;                    && 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 );

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