欢迎您访问程序员文章站本站旨在为大家提供分享程序员计算机编程知识!
您现在的位置是: 首页  >  IT编程

jQuery Callbacks完整功能代码详解

程序员文章站 2023-11-14 13:42:28
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...

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 );