var showad = true;
var Toppx = 0;			//上端位置
var AdDivW = 105;		//宽度（图片）
var AdDivH = 387;		//高度（图片）
var PageWidth = 800;	//页面多少宽度象素下正好不出现左右滚动条
var MinScreenW = 1024;	//显示广告的最小屏幕宽度象素
var ClosebuttonHtml = '<div align="right" style="position: absolute;top:387px;right:0px;margin:2px;padding:2px;z-index:2000;"><a href="javascript:" onclick="hidead()" style="color:white;text-decoration:none;font-size:12px;">关闭</a></div>'


var ClosebuttonHtml2 = '<div align="right" style="position: absolute;top:387px;right:0px;margin:2px;padding:2px;z-index:2000;"><a href="javascript:" onclick="hidead2()" style="color:white;text-decoration:none;font-size:12px;">关闭</a></div>'


var AdContentHtml = '<div align="center" style="color:green;font-size:23pt;font-family:黑体;"><img src=/ad/a1.jpg width=105 height=387 bord=0 ></div>';

var AdContentHtml2 = '<div align="center" style="color:green;font-size:23pt;font-family:黑体;"><img src=/ad/a2.jpg width=105 height=387 bord=0 ></div>';




document.write ('<div id="Javascript.LeftDiv" style="position: absolute;border: 1px solid #336699;z-index:1000;width:'+AdDivW+'px;height:'+AdDivH+'px;top:-1000px;word-break:break-all;display:none;">'+ClosebuttonHtml+'<div>'+AdContentHtml+'</div></div>');
document.write ('<div id="Javascript.RightDiv" style="position: absolute;border: 1px solid #336699;z-index:1000;width:'+AdDivW+'px;height:'+AdDivH+'px;top:-1000px;word-break:break-all;display:none;">'+ClosebuttonHtml2+'<div>'+AdContentHtml2+'</div></div>');
function scall(){
	if(!showad){return;}
	if (window.screen.width<MinScreenW){
		alert("临时提示：\n\n显示器分辨率宽度小于"+MinScreenW+",不显示广告");
		showad = false;
		document.getElementById("Javascript.LeftDiv").style.display="none";
		document.getElementById("Javascript.RightDiv").style.display="none";
		return;
	}
	var Borderpx = ((window.screen.width-PageWidth)/2-AdDivW)/2;
	document.getElementById("Javascript.LeftDiv").style.display="";
	document.getElementById("Javascript.LeftDiv").style.top=document.body.scrollTop+Toppx;
	document.getElementById("Javascript.LeftDiv").style.left=document.body.scrollLeft+Borderpx;
	document.getElementById("Javascript.RightDiv").style.display="";
	document.getElementById("Javascript.RightDiv").style.top=document.body.scrollTop+Toppx;
	document.getElementById("Javascript.RightDiv").style.left=document.body.scrollLeft+document.body.clientWidth-document.getElementById("Javascript.RightDiv").offsetWidth-Borderpx;
}
function hidead()
{
	showad = false;
	document.getElementById("Javascript.LeftDiv").style.display="none";
	
}
function hidead2()
{
	showad = false;
	document.getElementById("Javascript.RightDiv").style.display="none";
	
}
window.onscroll=scall;
window.onresize=scall;
window.onload=scall;
<a href=></a>