jquery.ui.widget 工作原理分析

 

/*!
 * jQuery UI Widget 1.8.15
 * $Id: jquery.ui.widget.js,v 1.3 2011/12/06 07:19:29 licongping Exp $
 * Copyright 2011, AUTHORS.txt (http://jqueryui.com/about)
 * Dual licensed under the MIT or GPL Version 2 licenses.
 * http://jquery.org/license
 *
 * http://docs.jquery.com/UI/Widget
 */
(function( $, undefined ) {

// jQuery 1.4+
if ( $.cleanData ) {
	var _cleanData = $.cleanData;
	// 重写cleanData方法，调用后触发每个元素的remove事件
	$.cleanData = function( elems ) {
		for ( var i = 0, elem; (elem = elems[i]) != null; i++ ) {
			$( elem ).triggerHandler( "remove" );
		}
		_cleanData( elems );
	};
} else {
	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" );
					});
				}
			}
			return _remove.call( $(this), selector, keepData );
		});
	};
}

$.widget = function( name, base, prototype ) {
	var namespace = name.split( "." )[ 0 ],
		fullName;
	name = name.split( "." )[ 1 ];
	fullName = namespace + "-" + name;
	// 例如参数name='om.tabs'，变成namespace='om',name='tabs',fullName='om-tabs'

	// base默认为Widget类，组件默认会继承base类的所有方法
	if ( !prototype ) {
		prototype = base;
		base = $.Widget;
	}

	// create selector for plugin
	$.expr[ ":" ][ fullName ] = function( elem ) {
		return !!$.data( elem, name );
	};

	// 创建命名空间$.om.tabs
	$[ namespace ] = $[ namespace ] || {};
	$[ namespace ][ name ] = function( options, element ) {
		// allow instantiation without initializing for simple inheritance
		if ( arguments.length ) {
			this._createWidget( options, element );
		}
	};

	// 初始化父类，一般调用了$.Widget
	var basePrototype = new base();
	// 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( true, {}, basePrototype.options );
	// 给om.tabs继承父类的所有原型方法和参数
	$[ namespace ][ name ].prototype = $.extend( true, basePrototype, {
		namespace: namespace,
		widgetName: name,
		// 组件的事件名前缀，调用_trigger的时候会默认给trigger的事件加上前缀
		// 例如_trigger('create')实际会触发'tabscreate'事件
		widgetEventPrefix: $[ namespace ][ name ].prototype.widgetEventPrefix || name,
		widgetBaseClass: fullName
	}, prototype );

	// 把tabs方法挂到jquery对象上，也就是$('#tab1').tabs();
	$.widget.bridge( name, $[ namespace ][ name ] );
};

$.widget.bridge = function( name, object ) {
	$.fn[ name ] = function( options ) {
		// 如果tabs方法第一个参数是string类型，则认为是调用组件的方法，否则调用options方法
		var isMethodCall = typeof options === "string",
			args = Array.prototype.slice.call( arguments, 1 ),
			returnValue = this;

		// allow multiple hashes to be passed on init
		options = !isMethodCall && args.length ?
			$.extend.apply( null, [ true, options ].concat(args) ) :
			options;

		// '_'开头的方法被认为是内部方法，不会被执行，如$('#tab1').tabs('_init')
		// prevent calls to internal methods
		if ( isMethodCall && options.charAt( 0 ) === "_" ) {
			return returnValue;
		}

		if ( isMethodCall ) {
			this.each(function() {
				// 执行组件方法
				var instance = $.data( this, name ),
					methodValue = instance && $.isFunction( instance[options] ) ?
						instance[ options ].apply( instance, args ) :
						instance;
				// TODO: add this back in 1.9 and use $.error() (see #5972)
//				if ( !instance ) {
//					throw "cannot call methods on " + name + " prior to initialization; " +
//						"attempted to call method '" + options + "'";
//				}
//				if ( !$.isFunction( instance[options] ) ) {
//					throw "no such method '" + options + "' for " + name + " widget instance";
//				}
//				var methodValue = instance[ options ].apply( instance, args );
				if ( methodValue !== instance && methodValue !== undefined ) {
					returnValue = methodValue;
					return false;
				}
			});
		} else {
			// 调用组件的options方法
			this.each(function() {
				var instance = $.data( this, name );
				if ( instance ) {
					// 设置options后再次调用_init方法，第一次调用是在_createWidget方法里面。这个方法需要开发者去实现。
					// 主要是当改变组件中某些参数后可能需要对组件进行重画
					instance.option( options || {} )._init();
				} else {
					// 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  
					$.data( this, name, new object( options, this ) );
				}
			});
		}

		return returnValue;
	};
};

$.Widget = function( options, element ) {
	// 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
	},
	_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
		$.data( element, this.widgetName, this );
		this.element = $( element );
		this.options = $.extend( true, {},
			this.options,
			this._getCreateOptions(),
			options );

		var self = this;
		this.element.bind( "remove." + this.widgetName, function() {
			self.destroy();
		});
		// 开发者实现
		this._create();
		// 如果绑定了初始化的回调函数，会在这里触发。注意绑定的事件名是需要加上前缀的，如$('#tab1').bind('tabscreate',function(){});
		this._trigger( "create" );
		// 开发者实现
		this._init();
	},
	_getCreateOptions: function() {
		return $.metadata && $.metadata.get( this.element[0] )[ this.widgetName ];
	},
	_create: function() {},
	_init: function() {},

	destroy: function() {
		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() {
		return this.element;
	},

	option: function( key, value ) {
		var options = key;

		if ( arguments.length === 0 ) {
			// don't return a reference to the internal hash
			return $.extend( {}, this.options ); // 返回组件的options
		}

		if  (typeof key === "string" ) {
			if ( value === undefined ) {
				return this.options[ key ]; // 获取值
			}
			options = {};
			options[ key ] = value;
		}

		this._setOptions( options ); // 设置值

		return this;
	},
	_setOptions: function( options ) {
		var self = this;
		$.each( options, function( key, value ) {
			self._setOption( key, value );
		});

		return this;
	},
	_setOption: function( key, value ) {
		this.options[ key ] = value;

		if ( key === "disabled" ) {
			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 );
	},

	// $.widget中优化过的trigger方法。可以同时调用config中的方法和bind的方法。
	// 即可以用两个方式去给组件绑定事件。如$("tabs").omTabs({"change":function(){//handler}});或者$("tabs").bind("tabschange",function(){//handler});
	_trigger: function( type, event, data ) {
		// 调用初始化配置config中的回调方法
		var callback = this.options[ type ];
		// 封装js标准event对象为jquery的Event对象
		event = $.Event( event );
		// 给事件名称加上前缀，前缀默认是组件的名字。如_trigger("change")实际会触发"tabschange"事件
		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 ) {
			for ( var i = $.event.props.length, prop; i; ) {
				prop = $.event.props[ --i ];
				event[ prop ] = event.originalEvent[ prop ];
			}
		}
		// 触发element中绑定的事件
		this.element.trigger( event, data );
		return !( $.isFunction(callback) &&
			callback.call( this.element[0], event, data ) === false ||
			event.isDefaultPrevented() );
	}
};

})( jQuery );