/* jQuery图片预加载插件。  */
jQuery.fn.loadthumb = function(options) {
	options = $.extend({
		 src : ""
	},options);
	var _self = this;
	
	_self.hide();
	var img = new Image();
	$(img).load(function(){
		_self.attr("src", options.src);
		_self.fadeIn("slow");
	}).attr("src", options.src);  //.attr("src",options.src)要放在load后面，

	return _self ;
}

$(document).ready(function(){
	 var len  = $(".num > li").length;
	 var index = 0;
	 var adTimer;
	 $(".num li").mouseover(function(){
		index  =   $(".num li").index(this);
		showImg(index);
	 }).eq(0).mouseover();	
	 //滑入 停止动画，滑出开始动画.
	 $('.ad').hover(function(){
			 clearInterval(adTimer);
		 },function(){
			 adTimer = setInterval(function(){
			    index++;
				if(index==len){index=0;}
				showImg(index);				
			  } , 5000);
	 }).trigger("mouseleave");
});

function showImg(index){
		//定义图片的src
		var src = ["/images/1zjzj.jpg","/images/3fenxiao.jpg","/images/4daixiao.jpg","/images/5danbao.jpg","/images/2tuiguang.jpg"];
		var oriUrl=["/?reg","/help_154_2.html","/help_151_2.html","/help_226_1.html","/help_129_2.html"];
		
		//指定url
		$(".ad a").attr("href",oriUrl[index]);
		//运用图片预加载插件
		$(".ad img").loadthumb({src:  src[index] });
		
		$(".num li").removeClass("on")
			.eq(index).addClass("on");
}