jQuery UI Widget(1.8.1)工作原理--转载

/*!
 * jQuery UI Widget 1.8.1
 *
 * Copyright (c) 2010 AUTHORS.txt (http://jqueryui.com/about)
 * Dual licensed under the MIT (MIT-LICENSE.txt)
 * and GPL (GPL-LICENSE.txt) licenses.
 *
 * http://docs.jquery.com/UI/Widget
 */
(function( $ ) {
 
var _remove = $.fn.remove;
 
$.fn.remove = function( selector, keepData ) {
    return this.each(function() {
        if ( !keepData ) {
            if ( !selector || $.filter( selector, [ this ] ).length ) {
                $( "*", this ).add( this ).each(function() {
                    $( this ).triggerHandler( "remove" );
                });
            }
        }
        //dom元素在被删除前，触发一下remove事件，jquery框架本身没有对元素删除绑定事件
        return _remove.call( $(this), selector, keepData );
    });
};
 
$.widget = function( name, base, prototype ) {
    var namespace = name.split( "." )[ 0 ],
        fullName;
    name = name.split( "." )[ 1 ];
    fullName = namespace + "-" + name;
    //比如ui.tab,上面的name=‘tab‘;fullName=‘ui-tab‘;
 
    if ( !prototype ) {
        prototype = base;
        base = $.Widget;
    }
    //如果没有prototype,那么prototype就是base参数,实际base默认为$.Widget
 
    // create selector for plugin
    $.expr[ ":" ][ fullName ] = function( elem ) {
        return !!$.data( elem, name );
    };
 
    $[ namespace ] = $[ namespace ] || {};//是否有命名空间
    $[ namespace ][ name ] = function( options, element ) {//根据上面的例子，即初始化了$.ui.tab=func
        // allow instantiation without initializing for simple inheritance
        if ( arguments.length ) {
            this._createWidget( options, element );
        }
    };
 
    var basePrototype = new base();//初始化，一般都是调用了new $.Widget()
    // we need to make the options hash a property directly on the new instance
    // otherwise we‘ll modify the options hash on the prototype that we‘re
    // inheriting from
//    $.each( basePrototype, function( key, val ) {
//        if ( $.isPlainObject(val) ) {
//            basePrototype[ key ] = $.extend( {}, val );
//        }
//    });
    basePrototype.options = $.extend( {}, basePrototype.options );//初始化options值，注意不需要深度拷贝
    $[ namespace ][ name ].prototype = $.extend( true, basePrototype, {
        namespace: namespace,
        widgetName: name,
        widgetEventPrefix: $[ namespace ][ name ].prototype.widgetEventPrefix || name,
        widgetBaseClass: fullName
    }, prototype );
    //为新的ui模块创建原型，使用深度拷贝，在basePrototype上扩展一些模块基本信息，在扩展prototype,比如ui.tabs.js中就是tab的拥有各种方法的大对象
 
    $.widget.bridge( name, $[ namespace ][ name ] );//将此方法挂在jQuery对象上
};
 
$.widget.bridge = function( name, object ) {
    $.fn[ name ] = function( options ) {
        var isMethodCall = typeof options === "string",
            args = Array.prototype.slice.call( arguments, 1 ),
            returnValue = this;
        //如果第一个参数是string类型，就认为是调用模块方法
        //剩下的参数作为方法的参数，后面会用到
 
        // allow multiple hashes to be passed on init
        options = !isMethodCall && args.length ?
            $.extend.apply( null, [ true, options ].concat(args) ) :
            options;
        //可以简单认为是$.extend(true,options,args[0],...),args可以是一个参数或是数组
 
        // prevent calls to internal methods
        if ( isMethodCall && options.substring( 0, 1 ) === "_" ) {
            return returnValue;
        }
        //开头带下划线的方法都是私有方法，不让调用
 
        if ( isMethodCall ) {//如果是调用函数
            this.each(function() {
                var instance = $.data( this, name ),//得到实例，实例作为一个数据和元素关联上
                    methodValue = instance && $.isFunction( instance[options] ) ?
                        instance[ options ].apply( instance, args ) ://如果实例和方法均存在，调用方法，把args作为参数传进去
                        instance;//否则返回undefined
                if ( methodValue !== instance && methodValue !== undefined ) {//如果methodValue不是jquery对象也不是undefined
                    returnValue = methodValue;
                    return false;//跳出each，一般获取options的值会走这个分支
                }
            });
        } else {//不是函数调用的话
            this.each(function() {
                var instance = $.data( this, name );
                if ( instance ) {//实例存在
                    if ( options ) {//有参数
                        instance.option( options );//调用option函数，一般是设置状态之类的操作
                    }
                    instance._init();//再次调用此函数，根据options调整
                } else {
                    $.data( this, name, new object( options, this ) );
                    //没有实例的话，给元素绑定一个实例。注意这里的this是dom，object是模块类
                }
            });
        }
 
        return returnValue;//返回，有可能是jquery对象，有可能是其他值
    };
};
 
$.Widget = function( options, element ) {//所有模块的基类
    // allow instantiation without initializing for simple inheritance
    if ( arguments.length ) {//如果有参数，调用初始化函数
        this._createWidget( options, element );
    }
};
 
$.Widget.prototype = {
    widgetName: "widget",
    widgetEventPrefix: "",
    options: {
        disabled: false
    },//上面的属性会在创建模块时被覆盖
    _createWidget: function( options, element ) {
        // $.widget.bridge stores the plugin instance, but we do it anyway
        // so that it‘s stored even before the _create function runs
        this.element = $( element ).data( this.widgetName, this );//缓存实例，保存jquery对象
        this.options = $.extend( true, {},
            this.options,
            $.metadata && $.metadata.get( element )[ this.widgetName ],
            options );//参数处理
 
        var self = this;
        this.element.bind( "remove." + this.widgetName, function() {
            self.destroy();
        });//注册销毁事件
 
        this._create();//创建
        this._init();//初始化
    },
    _create: function() {},
    _init: function() {},
 
    destroy: function() {//销毁模块：去除绑定事件、去除数据、去除样式、属性
        this.element
            .unbind( "." + this.widgetName )
            .removeData( this.widgetName );
        this.widget()
            .unbind( "." + this.widgetName )
            .removeAttr( "aria-disabled" )
            .removeClass(
                this.widgetBaseClass + "-disabled " +
                "ui-state-disabled" );
    },
 
    widget: function() {//返回jquery对象
        return this.element;
    },
 
    option: function( key, value ) {//设置选项函数
        var options = key,
            self = this;
 
        if ( arguments.length === 0 ) {
            // don‘t return a reference to the internal hash
            return $.extend( {}, self.options );//返回一个新的对象，不是内部数据的引用
        }
 
        if  (typeof key === "string" ) {
            if ( value === undefined ) {
                return this.options[ key ];//取值
            }
            options = {};
            options[ key ] = value;//设置值
        }
 
        $.each( options, function( key, value ) {
            self._setOption( key, value );//调用内部的_setOption
        });
 
        return self;
    },
    _setOption: function( key, value ) {
        this.options[ key ] = value;
 
        if ( key === "disabled" ) {//增加或是去除className
            this.widget()
                [ value ? "addClass" : "removeClass"](
                    this.widgetBaseClass + "-disabled" + " " +
                    "ui-state-disabled" )
                .attr( "aria-disabled", value );
        }
 
        return this;
    },
 
    enable: function() {
        return this._setOption( "disabled", false );
    },
    disable: function() {
        return this._setOption( "disabled", true );
    },
 
    _trigger: function( type, event, data ) {
        var callback = this.options[ type ];
 
        event = $.Event( event );
        event.type = ( type === this.widgetEventPrefix ?
            type :
            this.widgetEventPrefix + type ).toLowerCase();
        data = data || {};
 
        // copy original event properties over to the new event
        // this would happen if we could call $.event.fix instead of $.Event
        // but we don‘t have a way to force an event to be fixed multiple times
        if ( event.originalEvent ) {//把原始的event属性重新赋到event变量上
            for ( var i = $.event.props.length, prop; i; ) {
                prop = $.event.props[ --i ];
                event[ prop ] = event.originalEvent[ prop ];
            }
        }
 
        this.element.trigger( event, data );
 
        return !( $.isFunction(callback) &&
            callback.call( this.element[0], event, data ) === false ||
            event.isDefaultPrevented() );
    }
};
 
})( jQuery );