fd-gulp-convert-encoding/test/source/qingguo/js/module/industryAd/sidebarfollow.js

convert file to assigned charset

/**
 * @author: mg12 [http://www.neoease.com/]
 * @update: 2012/12/05
 */

SidebarFollow = function() {

	this.config = {
		element: null, // �����Ľڵ�
		distanceToTop: 0 // �ڵ��ϱߵ�ҳ�涥���ľ���
	};

	this.cache = {
		originalToTop: 0, // ԭ����ҳ�涥���ľ���
		prevElement: null, // ��һ���ڵ�
		parentToTop: 0, // ���ڵ���ϱߵ���������
		placeholder: jQuery('<div>') // ռλ�ڵ�
	}
};

SidebarFollow.prototype = {

	init: function(config) {
		this.config = config || this.config;
		var _self = this;
		var element = jQuery(_self.config.element);
        _self.isIE6 = false;
        _self.originalOffeset = element.offset().top;

        jQuery.browser.version === "6.0" ? _self.isIE6 = true : _self.isIE6 = false;

		// ���û���ҵ��ڵ�, �����д���
		if(element.length <= 0) {
			return;
		}

		// ��ȡ��һ���ڵ�
		var prevElement = element.prev();
		while(prevElement.is(':hidden')) {
			prevElement = prevElement.prev();
			if(prevElement.length <= 0) {
				break;
			}
		}
		_self.cache.prevElement = prevElement;

		// ���㸸�ڵ���ϱߵ���������
		var parent = element.parent();
		var parentToTop = parent.offset().top;
		var parentBorderTop = parent.css('border-top');
		var parentPaddingTop = parent.css('padding-top');
		_self.cache.parentToTop = parentToTop + parentBorderTop + parentPaddingTop;

		// ������Ļ
		jQuery(window).scroll(function() {
			_self._scrollScreen({element:element, _self:_self});
            if( _self.isIE6 ){
                _self._fixIE6({element:element, _self:_self});
            }

		});

		// �ı���Ļ�ߴ�
		jQuery(window).resize(function() {
			_self._scrollScreen({element:element, _self:_self});
            if( _self.isIE6 ){
                _self._fixIE6({element:element, _self:_self});
            }
		});
	},

	/**
	 * �޸Ľڵ�λ��
	 */
	_scrollScreen: function(args) {
		var _self = args._self;
		var element = args.element;
		var prevElement = _self.cache.prevElement;

		// ��õ������ľ���
		var toTop = _self.config.distanceToTop;

		// ��� body �� top ����, ������Щλ��
		var bodyToTop = parseInt(jQuery('body').css('top'), 10);
		if(!isNaN(bodyToTop)) {
			toTop += bodyToTop;
		}

		// ��õ������ľ��Ծ���
		var elementToTop = element.offset().top - toTop;

		// ���������һ���ڵ�, ��õ���һ���ڵ�ľ���; ������㵽���ڵ㶥���ľ���
		var referenceToTop = 0;
		if(prevElement && prevElement.length === 1) {
			referenceToTop = prevElement.offset().top + prevElement.outerHeight();
		} else {
			referenceToTop = _self.cache.parentToTop - toTop;
		}

		// ���ڵ�����������, �������
		if(jQuery(document).scrollTop() > elementToTop) {
			// ����ռλ�ڵ�
			var elementHeight = element.outerHeight();
			_self.cache.placeholder.css('height', elementHeight).insertBefore(element);
			// ��¼ԭλ��
			_self.cache.originalToTop = elementToTop;
			// �޸���ʽ

            element.css({
                top: toTop + 'px',
                position: 'fixed'
            });


		// ����ص�ԭλ
		} else if(_self.cache.originalToTop > elementToTop || referenceToTop > elementToTop) {
			// ɾ��ռλ�ڵ�
			_self.cache.placeholder.remove();
			// �޸���ʽ
			element.css({
				position: 'static'
			});
		}
	},

    _fixIE6: function(args) {
        var _self = args._self;
        var element = args.element;

        if (_self.originalOffeset + 450 < jQuery(document).scrollTop() ) {
            element.css({
                top: jQuery(document).scrollTop() - 190 + 'px',
                position: 'absolute'
            });
        } else {
            element.css({
                position: 'static'
            });
        }

    }
};